Along with all these other good suggestions, keep in mind that pack size and weight are not necessarily related. Winter gear for example, is bulky, but not necessarily heavy, things like parka, insulated pants. extra gloves, hats, etc.

Minimal is in the eye of the beholder. Some people are happy with a tarp and a quilt, soda can stove and not much else. Others want a tent, sleeping bag, gas stove of some kind, cooking gear and other comforts. This is why we recommend getting your gear first.

However, if there isn't a store near you, this is a challenge. You can buy online from REI and send back whatever you buy if it turns out not to fit or isn't big enough or any other reason, for that matter.

Used gear or renting at first is a good idea, but it helps if you know what you are looking at. Not all used packs are bargains, some will be just cheap, not well made to begin with and may not last long or fit right.

For used gear, I would stick to brand names and you can get plenty of advice here if you come across something you don't know anything about.