Another question that new and experienced Camino pilgrims talk about and constantly reassess regards what gear to take.  The answers are highly personal to each pilgrim as well as to each Camino so there are no right or wrong things on the list.  That said, in general this is what works for me in Spain, Italy or southern France in the Spring or Autumn:

Walking boots – I like low ankle Keen Targhee II boots.  They have a wide toe box and they are comfortable right out of the box.  The low-cut means I have less ankle support on tougher sections of trail and the occasional pebble in the boot but I prefer the comfort of these.  None-the-less, they must have at least 100km on them before walking a Camino.
Sandals – Again, I take Keens Newport H2 although I am still looking for the perfect second shoe.  I like these because they can be used on the trail if need be, they protect our toes at all times and they can be used with or without socks anywhere without looking dorky or too inappropriate. What I don’t like about them is that they are heavier and bulkier than alternative footwear.  For second shoes, I have tried using Crocs, flip-flops, Teva Hurricanes and Xero Umara Z-Trails and I’ve not been thrilled with any of them for various reasons.  They are all lighter and smaller than the Keens but I could not walk for miles in them.
Flip-flops – Melanie always takes a light, cheap pair of these rubber beachwear to walk to, from and in the shower.  I do without as I don’t think they are worth the extra weight.
Long pants – two pairs – I normally walk in shorts so these are my travelling, sightseeing and evening wear.  Both pairs are lightweight, cargo pants (Northface, Columbia or REI) but one pair have zip-off lower legs.  This second pair is my replacement or alternative to either set of pants in case the primary pants are wet, dirty or torn.
Walking shorts – one pair – lightweight, cargo pants (Northface, Columbia or REI).  I have used shorts every day of every walk except the first day – and hated walking over the Pyrenees in long pants.  I have walked through bramble, through mountain passes in zero degrees and through major cities in shorts and only needed something longer in sub-zero weather or side-ways rain
Walking shirts – three – Call me old-fashioned but I use short sleeve, button-down, lightweight, plaid, Columbia brand shirts. They work for me. One is to walk in. The second is for evening wear or as a replacement if the first is wet, dirty or torn.  The third one is for travelling and wearing before or after the walk.  I usually use my oldest shirt for the daily walk and they tend to get in pretty bad shape by the end of the walk, if they last that long.  You might get away with only two shirts.
Undershirts – four – I use a short sleeve, compression Under Armour shirt while walking.  It keeps me cooler or warmer as needed and I carry two of them. Again, the second one is for when the first one is dirty or wet.  I also carry two very lightweight Uniqlo V-neck AIRism undershirt for travel, evenings and pre- and post-Camino.  They all dry quickly when washed.
Underpants – four pair – I use a Under Armour boxer shorts while walking.  They also keep me cooler or warmer as needed and I carry two of them.  It’s no surprise by now that one is for when the other is dirty or wet.  I also carry two pair of Exofficio travel underwear for travel, evenings and pre- and post-Camino.  Again, these all wash and dry quite easily and fast.
Hiking socks– two pair – I am partial to mid-weight Smartwool hiking socks.  These guys can last two weeks or more between washing and they don’t smell.  They need a dryer when washed though so it may be two weeks between washes!  The second pair is for when the first pair is wet from rain, mud or emergency washing.  It also comes in handy if the I’m using an old pair and they develop a hole.
Sock liners – two pair – More than anything else, these are what save me from blisters.  I usually have two pair of liners and use what seems appropriate for the day ahead.  I carry one pair of REI silk liners and one Fox River X-Static
Other Socks – two pair – I know!  Six pairs of socks?!?!  I carry thin travel socks to keep my feet from swelling on the plane.  For me, they are worth the weight.  I also carry a pair of black lightweight Ice-Breaker merino wool hiking socks for cooler evenings and sightseeing under my sandals.  They will also be used if I ever need to hike in the sandals.  They are merino wool and they need to get washed less frequently than the underside of my car.
Sleeping pants – two pair – When not sleeping in albergues, I sleep in cotton boxers for comfort.  In the albergues or hostals, I try to keep other pilgrims in mind and wear a pair of lightweight running shorts over my boxers.
T-shirt – I have one t-shirt for sleeping in the albergues if it is cold or for hanging out in the albergue.  Occasionally, I also use it for evenings for a change from the button-down shirt.
Pullover – I used to carry a zip-up fleece but found that the bulk did not make up for the added warmth.  I have since changed to a lightweight Northface sweater-jacket that I can no longer find in their catalogue.  It’s not waterproof but it’s warm.  Evenings & the hills in southern Europe can still be quite chilly in the Spring & Fall.
Rain pants – I have only needed these on one day on my first Camino, two times on subsequent Caminos and five days on the English C2C walk but I think they are worth the weight.  I can walk in fairly heavy rain wearing only shorts but several times, when the rain was whipping sideways and the temperature was near freezing, the rain pants saved either my life or my day, depending on the decisions that I made.  If I expect to walk a lot using the pants all day, I will wear running tights under them, instead of shorts.  That keeps me warmer and not as clammy.
Rain jacket – We have our beloved Altus Atmospheric Light backpacker rain jackets that fit over our backpacks.  They are very-well used by now but get re-waterproofed every year.  We love these because they make sure our gear stays dry and we stay warm in the rain.  They don’t vent very well but with careful management, we can usually stay mostly dry from condensation underneath.
Wide-brimmed hat – This is mandatory unless you like skin cancer and carrying tons of sunscreen.  After trying out several brands, I have settled on the Sunday Afternoon’s Cruiser hat.  It can still look good after being compressed in a backpack and the brim is strong enough not to flop in my face in the slightest breeze.  It keeps me cool in the blazing sun.
Ballcap– I use a fairly cheap runners’ peaked ball cap under my rain jacket hood to keep the rain off my face.  The peak is plastic inside, rather than cardboard so it doesn’t droop.
Buff– This keeps my face, neck, ears and/or head warm when needed.  It isn’t often used but every walk, I need it a few times.
Arm covers – Motorcyclists in Singapore inspired this.  These cover my forearms to keep them warm in the early morning or mountains and also are used at times as a sunblock later in the day.  I could just walk in long sleeves and roil them up but that would not be as warm and I hate the bulk of a rolled-up sleeve.
Hiking gloves – If we are expecting cold, I take a pair of thin fleece gloves for the mornings.  I don’t use them as much as Melanie but they do come in handy.
Beanie– two – I shave my head so these are my artificial hair for staying warm and keeping the sun off at times.  One is very thin, more of a skull cap and the other is for slightly colder weather.  I use them both when it is really cold.
Sarong – This is the most useful thing I carry.  I use it every day, more so in the albergues than the more private accommodations.  It is a typical Malay or Indian cotton sarong that has the two ends sewn together so it in more tubular shape.  It is lightweight, dries quickly and is multi-purposed.  I use it for changing modestly before and after a shower, it acts as a “finishing-off” towel, and at night, it is used either as a pillow case or a privacy screen.

Backpack – I currently used a 45-liter REI Flashpack.  I used to have a 40+10-litre Deuter bag that I loved but it was pretty well used.  I walked into REI to buy an Osprey Exos 48 but got talked into the cheaper REI bag by staff.  I’m sort of happy with the REI bag but it squeaks when I walk sometimes and my waist gets drenched with sweat.  I’m slowly learning to like it but also currently looking forward to the day it needs to be replaced.
Rain cover – this cover for the backpack is used whenever we think rain is possible on the walk.  For a light drizzle, I may not put on the Altus and the rain cover still keeps my gear dry.  Some people would think the Altus over the backpack rain cover is overkill but I would hate arriving in a town and all my gear is wet.
Waist pouch – I carry a Zpack 4in1 Multi-pack.  It’s a bit specialized and expensive but it’s perfectly waterproof and strong.  It carries my wallet, passport, credentials, iPhone, local phone and anything else small that I need to get my hands on quickly.  I wear mine over one shoulder but it can also be used as a waist pouch, a front pouch for the backpack, a strap-on attachment to the backpack or a safe bag in the backpack.
Scrubba Bag – this glorified dry bag is a luxury item to carry. While it doesn’t weigh a lot, it isn’t really needed but it makes laundry duties easier and less messy. In albergues, it saves me from queueing for limited basin space and in other accommodations, it keeps me from splashing water all over the place. I justify the extra weight because it allows me to carry less liquid laundry soap.
Day pack – I have a featherweight, waterproof daypack (Sea to Summit Ultra-Sil Dry) that rolls up to the size of a golf ball which is mainly useful for pre- and post-Camino sightseeing. It acts as a dry bag for electronics in my backpack at other times. (90gm)
Hiking poles – Every pilgrim has their opinions about whether these are needed at all, whether they should have rubber tips or not and whether fancier, more expensive sticks are worth the cost over cheap ones.  I am very, very happy with my Black Diamond Trail Pro Shock Trekking Poles with rubber tips. I only use my poles when climbing, descending or on very uneven ground but I could not imagine doing a Camino without these. I also carry a pair of replacement rubber tips. I lose one or two tips to mud or bridge grates almost every walk.

Camp towel– Actually, since my first Camino, I have only used a normal washcloth.  After showering with it, I rinse it off and then use it as a towel, wringing it out as needed.  I have no need for a towel at all.  For that last tiny bit of moisture, if needed, I use my sarong to completely dry off.
Sleeping sack – I use a Sea to Summit Silk Travel Liner.  I have never felt a need for a sleeping bag.  This saves me a lot of space and weight in my backpack. On the very few occasions that I have been cold at night, I just added an albergue blanket or t-shirt, long pants and/or a beanie.
Phone & charger – two! – I have a very small, 1993 style phone for emergencies and making reservations.  It is easy to get a local SIM card with €10 of credit for local calls. I also use an iPhone 6 for the camera (using the Pro HDR X app) and for GPS (using maps.me).  I also need to be contactable on my normal number so I keep two phones.
iPad-mini & charger – I find this perfect for blogging.  I can no longer use it for Google’s Blogger app but I figured out how to use WordPress and life is easy again.  I also store e-mailed and password protected copies of our passports, credit cards, bank cards, etc. as well as travel plans, emergency numbers and transportation tickets.
Electric adapter – I use a very small adapter that has universal inputs but just the two round plugs for Spanish outlets.
Portable charger – Cygnett 6,000mah, I can’t always get access to an albergue outlet and I never want to want to run out of batteries on the trail.  This unit is small and light but can fully recharge my phone four times.
Sunglasses – wrap-around, polarized with neckstring
Reading glasses & case – I’m getting old.  What to do?
Torch or headlamp & batteries – I use one or the other but only one is needed.  We often start walking before dawn.
Water bottles & bottle carrier – two – I carry Camelback Chute 750ml bottles because the caps are perfectly designed for backpackers.  I never drop the lid, get the mouthpiece dirty or waste water.  I carry one in a light carrier that is attached to my backpack strap, near my chest.  The other is in a backpack pocket that I can reach without taking off the backpack.
Swiss army knife – always useful for something.
Soap & holder – I use bar soap and a cheap plastic soap travel container.
Notebook & pen – a small notebook for writing notes , list and other memories.
Clothesline & 18 small paper binder clips (and a couple of safety pins) – Another extremely useful piece of equipment.  Often when we wash our gear in albergues, we are too late to get space on the clothes line.  Sometimes there is space but it is in the shade.  Being able to hang my own line has saved me many times.  When we stay in a hotel, B&B or other private room, we often have to hang up our gear overnight in the room.  Again, this clothesline saves the day.  The binder clips work better than clothespins or pins because of bulk or putting holes in my clothes.  I do bring a few pins though, in case I have to be a walking clothesline to dry out socks.

Other
Passport
Money – I start with about €300-500 and replenish at ATM’s that are available in bigger cities
Wallet
Pilgrim’s Credencial – I usually order this ahead of time from one of the Confraternities.
Flight tickets
Travel insurance card
ATM, credit cards
Bank account security dongles
Frequent Flier card

Dop Kit – Toothpaste, toothbrush, shave cream, razor, blister pads, ear plugs, sun cream, deodorant, melatonin, ibuprofen, Airborne multi-vitamin, band-aids, nail clippers, Woolite

The hiking poles and knife need to be in checked baggage. A mailing tube, taped up PVC drain pipe or hand folded and taped cardboard work fine. Alternatively, everything (except passport, tickets, money, etc.) could go into the checked baggage and just wrap everything in plastic wrap