Try watching Trick2G. He is a good jungler and you will learn so much from him.
However, I will give you some advice. Whenever you are ganking someone, ask yourself, is this player overextending his lane? Do we have enough crowd control to immobilize the opponent? Does he have wards / trinket? It is crucial to have map awareness and you should trust your instincts. Always remember to do a timer for blue and red golems as well as dragon and baron. Golems spawn every 5 mins. Dragon spawn every 6 mins. Baron spawn every 7 min. It would be ideal if you enable your time stamp on your settings in League.