Try and keep up with laner experience via farming your jungle. your unlikely to be able to keep up with a solo lane but you want to at least be on a par with botlane barring good reasons why not.
Help lanes who are behind via ganks, I say lanes who are behind because generally ahead will not be easy to do much in and I'm just trying to give a basic overview.
Attempt to counterjungle the enemies jungler. speaks for itself really.
calls on objective control. your the guy with the smite! you decide if your team goes for an early dragon. and making that call can be difficult at times. but if you have just killed their botlane or you just saw their jungler top you can steal drake straight out from under them.
Map awareness seeing as you dont have to constantly worry about an opponent you need to be keeping your team abreast of anything suspicious happening on the map and ward occasionally seeing as it is not as far out of your way to ward river ect.
So. farming. counterjungling controlling objectives and vision. I'm sure I missed something but yeah.thats the basics IMO