Thus far, at the beginning, I typically buy items or use ones obtained from quests, while later on I've smithed and enchanted weapons and shields myself, and used a combination of Thieves Guild and Nightinggale armor which I've upgraded myself.
I've just started a new game with a character who cannot craft anything (including upgrading), so he'll only be using whatever he can buy, loot from enemies, or receives from a quest - and he won't be in the Thieves Guild, so my favorite armor is a no-go this time around. Definitely a new experience and a challenge for me. After this game I plan to play a character who can't buy anything, so he'll be limited to whatever he can craft (might be tough since he won't be able to buy the materials), loot, steal, or receive from quests.