To Garen Jungle, you first need to understand that early game there will be little damage. Back after your first 2 camps, but pots and just save up for your first jungle item. Do not attempt dragon unless your laners are willing to help. Ganking Lanes as Garen is only possible when they are shoved up. Once you have purchased frozen mallets your ganks will become much better and will most likely result in kills. In team fights try to focus their ADC with your Q and Ult, and if they are in the back-Line Just E and W through the enemy team. If you ever run low just auto attack and regen.