Welcome in my Graves guide, it's my first guide here, and I won't write a lot, because I have played only about 15matches with Graves.
First thing I have to say is that I like when someone tell me what I did wrong, explain why and let me change it to better without voting bad.
I saw a lot of guides there, I know how nice they are done, and I know that I'm probably bad.
Graves is my favourite champion since he came out.
I hope you'll enjoy it! (also sorry if my english isn't fine)

I recommend those runes, you can anyway use own ones, but I don't prefeer other, if you don't have enough IP to get 'em just play without, but do not play ranked matches.

21-0-9 on AD carry, because it boosts your total damage.

You should always lasthit in your lane, you can go mid, but remeber to not push too much.
Killing someone and dying by turret isn't good idea, it's just not worth it, so if you can't finish someone, just leave him and farm creeps, push etc. If enemy team has karthus, tell your teammates when he reaches 6lvl, if you have Caitlyn or Ezreal etc. on your lane, don't let yourself get less than 200hp. You can kill enemy who is trying to B with less than 200hp by just using your Quickdraw -> Collateral Damage

DO NOT EVER GO INTO CENTER OF TEAMFIGHT
You should shoot W on enemy team first so it will slow them and do some damage, then let your team go there, try to attack low health champions first, like AP's and AD Carries like you. If you see that someone is attacking you, try to run out of his range, and then attack him back.