I've had a request to do a post about what to pack when coming to Ecuador. Of course I can only speak to what is helpful to have here in Cotacachi but there are some generalities that will apply to pretty much the whole country.
First of all, it's going to be important to know if you'll be able to go to some of the larger store available in the bigger cities. If you're on a tour, that may not work out well and you'll probably already know you need to bring everything but the kitchen sink. If, however, you're on your own, you can get most everything here that you can get where you're coming from. Some of it will be more expensive, some may cost less.
Secondly, are you coming for a visit or are you moving here? ("Moving here" includes spending six months in a short term rental.)
Be sure to bring all the prescription medications you need with you. You may have been told how much less expensive medications are here and for many of them, that's true. It's also true that you may not have to have a prescription for most meds you are accustomed to getting in the U.S. (and I'm guessing many other countries as well). That may be true--it may not. One of the medications I take is a lot more expensive here than it was in the States because they don't sell the generic here. I have no idea why that is but it is and that's what I have to deal with. The other ones I take are less expensive or close to what I was paying there. It's a great idea to check on meds while you're here. You may want to buy some to take home with you. If you want to take back quite a bit of it, you may have to be prepared to go to more than one pharmacy to get as much as you want. I can often only get enough for a couple of weeks at a time but this is a small town and that may well be the reason for that.
Wherever you go, unless you travel first class, you probably won't need anything other than casual clothes. If you're not a small size (both clothing and shoes) be sure you have enough even if something happens to one of your outfits or pair of shoes. You're not going to find large-ish sizes here. Sensible walking shoes are a must. The streets and sidewalks are frequently paving stones rather than blacktop or concrete. I have a pair of sandals I haven't worn since I got here. That may be different on the coast.
Toiletries: You can get just about anything here that you can get in the States--frequently not the same brands but the type of item is probably going to be available. If you use a razor with those little pieces with the fresh blade in them (no clue what they're called) you may want to bring as many as you'll need or plan on using disposables here. Sun screen is not only expensive here, I've been told it's not a high quality product.
Even in the rainy season sunglasses are a good idea. When the sun is shining, it's very bright. A hat is also a good idea but you can get one of those here are a good price so it's not essential.
As with many places you may travel, getting laundry done may be difficult or quite expensive so having some things you can wash out in a sink (that probably won't have hot running water) and will dry overnight is probably a good idea. Here in Cotacachi some of the hostals use my favorite laundry guy and he will pick up clothes in the morning and drop them off that same evening for 50 cents per pound. That's one heck of a good price. You might want to check with wherever you'll be staying to ask about their laundry availability and prices.
What I miss here that I haven't seen yet (and might be around somewhere if I searched enough):
Shower cleaning spray--you know, the stuff you spray on your shower walls to make sure they don't get all cruddy. We have VERY hard water here and unless I keep after them diligently, I get nasty water stains that eventually will turn into mineral deposits (I've seen them in other homes and my sink is starting to get the very beginnings of it). Back in the States, a quick spray every other day or so took care of that very nicely. A good, in-the-tank toilet bowl cleaner--it's not essential but it's nice. Books in English--there are a couple of stores in Quito that sell used English language books but that's about it. There are a couple of places here in Cotacachi who also have a limited selection of used books. My Kindle is (as you've read before) invaluable! I don't know what I'd do if I didn't have that availability for downloading books to read, both purchased and library books.
Shopping bag(s)--I'm talking about the canvas bags or string bags for groceries or other purchases back in the States. Most places you go will have plastic bags to put purchases in but I like being able to put all those little bags in one larger one or to just put the individual items I purchase in one bag. They're easier to carry and you can easily carry the very lightweight ones in your purse. I make string bags to carry around in my purse--they work great.
Coin purse--these are available by the dozen here but it's not a bad idea to start out with one and then pick out the one you really want after you've been shopping for a while. Carrying change with you is a very good idea. Stores here have far less change than we're accustomed to and it's always good to have the makings for change--this applies only in regular stores. The fresh markets and tourist markets all charge in even prices--the little things are 25 or 50 cents and the larger things are in even dollars. You'll also appreciate having a coin purse because most single dollars are coins, not bills. A coin purse is far better than having change in a pocket of a wallet. It's best to have a single container for change and bills in another place, preferably a front pocket.
Paper money--bring lots of small bills with you. Don't bring anything over a $20 bill unless you plan to pay for large items while you're here. It's frequently difficult (if not impossible) to break a $20 or even $10 bill at smaller places. A friend of mine had to buy two stamps at the post office because the woman didn't have change for $1--that's not common but it's an example of what you may run into. Oh, and banks generally won't make change for you--seriously! There's one bank here that will change $20 bills to $5's but you have to give them two days notice--yep, I really mean it. I get my cash from an ATM so I start out with $20 bills. I always start with that and see if whoever I'm doing business with can make change. If not, I pull out a $10 and, finally a $5. I horde the small stuff for when it's really needed. Shortly after I arrived here I took a taxi somewhere and when I handed him a $20 bill he started counting out $1 coins. He had enough but it took him down to his last one or two. So, think small when you think money.
Whatever you pack, be sure to leave plenty of room for packing things to take home with you. I know people who bring one suitcase with a canvas-style duffel packed in it to use to carry home their purchases. The one I used when I cam here--in fact I moved here with five of them--Samsonite Tote-A-Ton (disclaimer: this is an affiliate link and if you choose to buy this product from this link, I will receive a small commission from the sale). They all made the trip in great condition and I have no doubt I could use them again and again, even travelling internationally. This is actually a very good idea unless you are one of those people who take home photos rather than "stuff."