I start at gromp with e. DONT USE YOUR POTIONS. Ask for a strong leash and smite it immediately. Make sure to ping your leashers away and type "ty" when they need to leave so they don't take your experience. Then go to blue. Make sure you use e right before blue hits you to take as little damage as possible. STILL DON'T USE POTIONS. Go to red. LAST HIT IT WITH SMITE AND DON'T USE A POTION UNTIL AFTER IT POPS YOUR PASSIVE. Now you have full health. Gank mid or top depending on which is pushed by your opponent. If neither is puhed, you can go kill their jungler or take one of his camps. Grab a couple more camps (raptors and wolves) then go back and buy.

In team fights you will want to flash q their biggest damage threat. (obviously don't flash if you can catch him or her out of position). Once you do, turn on your ult and pop your randuins as you should be in the middle of the team. The team will be slowed and taking your aoe hits (or throwing everything on you). This will give your team time to get some aoe cc and heavy damage down. Your job is just to flip their carry and tank. It is ok to die if your team is following you up. Don't go in if your team can't/won't follow you. If you are underfed but your adc is fed you can just peel for her. There is no need to dive in if you can't tank for very long and they have no serious targets.