These things are based on my personal experiences and some others.

Tip 1:
Catch every pokemon you get.
Also save up the candy they give.
Once you get a lucky egg evolve all your "crappy" pokemons and you'll be getting 1000 exp per evolution. (Can let you skip a huge amount of effort and time in the long run).

Tip 2:
Never use stardust unless high level.
You only really need stardust at the point when your player level is capped.
Your player level will resemble what cp pokemons you find in the wild which basically means that low level stardust usage is a huge mistake since you encounter higher cp's along the way.

Tip 3:
Pokemon modules (pokelures) can actually stack up if the pokestops are close enough to eachother (aka being able to open them both without the other being unavailable).
Incenses and pokemon modules (pokelures) stack aswell.

Tip 4.
Pokemons have fixed spawn positions with a small radius around that position.
You'll notice this if you open pokemon go at your house and keepctrack of where the pokemons spawn.
Seeing a pokemon in one position pretty much means it can spawn there again.

Tip 5.
Try to get pokemon eggs(can get them at pokestops, have to be lucky though)
They can hatch pokemons that aren't available in your area plus 10km eggs can hatch the strongest pokemons.

Tip 6.
Don't get attached to pokemons since you're gonna have to transfer them eventually anyways if you're still leveling up your player(unless you prefer low cp pokemons that take up space ofcourse).