Get resources, barracks, walls, defense buildings, army camps maxed out first?
It depends on your and your clan's priorities
If you're in a clan that prioritizes clan wars, you probably want to maximize your attack as quickly as possible - camps, barracks, laboratory, key troop upgrades, spell factory. That's all elixir stuff, so you can use the gold that's lying around to work on walls.
Alternately, if you prioritize farming, barracks aren't so important to rush, because you don't need dragons or pekkas to farm (in my experience). But it's nice to get the army camps up so that you can maximize your resource raiding.
I try to take a balanced approach. When I first upgrade my townhall, I try to get all the new buildings in place, and get them up to the level of their siblings as quickly as possible, and upgrade my laboratory immediately. I most recently went to TH8, so I didn't have army camp upgrades to worry about, or mines/collectors. So, I've been rotating through my defenses, and working on at most one barracks upgrade at a time: dark barracks to level 3, barracks to level 10, new dark barracks... That's as far as I've gotten so far. Oh, and I got my dark elixir drill to level 3 as fast as I could. I'm trying to get my air defenses to level 6 quickly, because dragon attacks are prevalent in clan wars at my level.
Don't know if this helps you much... The bottom line is, keep your builders busy and your laboratory burning! Prioritize the troops you use most, but ultimately try to keep up with all of them, because they're all pretty cool at high levels.