I'm a jg main and I'm here to help! First and foremost, the new patch has completely changed the way jg is played, mostly for the worse. Because of new smite and the new devourer, junglers have a much stronger mid-late game, but early game is HELL. First and foremost, building armor on your runes will help tremendously, because that is really the only way to overcome the huge damage spike in monster camps. Potions are a must regardless of who you play. Many of the squishier junglers who were awesome season 4 (nocturne, evelynn etc.) are completely unviable now, so if you are new to jg limit yourself to tanky junglers (chogath, malphite, skarner etc.) or champs with HP sustain (master yi, warwick, udyr, nasus etc.). And ignore your teammates if they bitch about you not ganking, the new jg makes it really hard to gank since you are always low on health, so only gank if you have a good amount of health. Also, jungle xp has been reduced so straight farming will no longer get you ahead of your enemies in level. What i like to do is offer to cover a lane while my teammate goes to buy items and heal, that way the lane is still pushed while i get xp and minion cs.