Anything mostly cotton should be avoided at all cost, it's the worst fabric for campers/hickers and is least recommended as it retains sweat and for cold weather doesn't retain heat very well. Stick with synthetics and silk liners are good for a variety of things. Of course for colder seasons, wool is good also for layering. Layering is best, so you may pair down or up and avoid big and bulky wear if possible.
I made all the mistakes in the beginning, cotton, cotton, cotton. Jeans, bad, but many people still wear them, they're just not the best hiking/camping material, soooo not breathable, some of the newer stretch blends are pretty good. I can't say enough good things about layering. Your base layer should be something that will keep moister from sticking to you, this is so important, polyesters and silks works well here, middle layer, fleece or natural fiber is good, I like merino wool, this to keep you warm. Your outer layer should be a material that's water repellent and breathable it's all going to depend on time of season as well, you want something wind resistant. You will modify all according to budget. You don't need to break the bank and can be quite economical, but, for those where money isn't an object, they make all kinds of clothing to suit the purpose just for these purposes, seasons be damned, all accompanied by sticker shock for some of us. LOL!