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There's just so much I could start telling you about, but honestly, you can find a lot of answers in this thread stuck to the top of the Pokémon GO board here:
Other than that, really the best advice I can give you is to just have fun with it. Part of the excitement for most of us was figuring the game out. I will say that the number one mistake I made when I started out was using my stardust to power up the weaker Pokémon I found in the beginning. You should really just horde all of that and wait until you're a much higher level to start powering up. You'll quickly find out your CP level caps for powering up aren't that high in comparison to what you'll be able to catch just a few trainer levels down the road.