Don't be afraid to buy wards if you have extra money. Vision is important to you and your entire team. You're going to be running through the river a lot and that puts you in a very vulnerable position if you have no vision.
Early game think about what teammate would snowball the hardest and camp their lane a bit. Its a bit of a dirty tactic, but it will make it easier for you to gank other lanes later. And it always nice to have another fed teammate helping with the ganks. :)
If your laner has a sliver of health and needs to back, offer to cover their lane. It does reveal your position to the enemy team but it will keep damage off your tower, keep your teammate alive, and you'll get some farm. Only shove it in if the enemy laner is gone. Otherwise just last hit until your teammate returns. They will love you for it.
Ping when you are going to a lane for ganks. In bot especially there's issues of people tunnel visioning while they farm. A small ping can help alert them that you are about to join then and try to make a play. Communication is key. ;D
Prep for taking dragon whenever you can. Keep vision around the pit as much as possible and later do the same for Baron. Both have very important buffs so denying them from the enemy is a big deal.
Mid to late game, give the red buff over to the adc. The slow helps a lot in the 5v5s and works great in combination with their late game items.