Basics

Your smite (knife item) gives you mana on hit + dmg over time, so start camps with the smite and use it on the biggest units. As a jungle clearing camps is very important so you need to choose either Overlord, Malady, or Breach. There are ways around it, but these items are great in teamfights too so theyre worth it. As most jungels the question will be how tanky is my team and how tanky do I want to be. Pretty much if the support and off lane are tank, then go dmg, if just off lane is tank then decide as you play how much tank you need, if there are no tanks, then just go overlord and max out your health.

Gameplay

As a jungle your job is to control the flow of the game, this is the hardest position game knowledge wise. Ganks do not need to kill, forcing a flash or a back is good enough, but you if you never get kills youll fall behind. Realize where wards are, or are commonly placed. Mid will place a river ward, watch for when they do it on the mini map and use it to your advantage. If you want an all in gank youll need to avoid the ward, if you dont want to gank but want to give your mid breathing room, just make an appearnce, make them think you want to gank so they play defensively. When you do gank its not always the best idea to blow a flash or dash right away even though it feels like it might be. If you are able to engage by walking up and save your dash it allows you to chase better or get out if things go wrong. Dont be too greedy on ganks, your death can screw the laner, but also dont be afraid to dive the turret. If you can kill them and flash away, you should.

Different to games like League of Legends ganking left and right have more impact because of the gold and xp buff. Not securing a kill can secure a free buff. When you do it, if you can push the minion wave under tower then pick it up.

Objectives as jungle

1. As you play make sure to drop wards in good places that your lanes wont be able to, you have the job of providing real jungle vision, so ward enemy buffs or high traffic cross roads. 1.5 at higher levels when people ward youll want to swap the ward out for a scanner, youll have time to ward one of your buffs (or the enemys), tp back, get the scanner, then go to your other buff, but work on 1 first before you jump to this
2. You need to get fangtooths and mini orb prime. They first one can be solo'd by most junglers with their first item. When they are up you should be ganking either your adc or offlane and allowing for a kill on one or the other.
3. Most importantly as jungle you want to set the tempo of the game. If your team has end game characters you need to help freeze lanes (pushing minions under towers resets the lane, ganking lanes pushing hard helps freeze the lane). If youre team is better early/mid game then you need to help push to end the game early. Getting mini prime can be an effective way to do this. All in all as jungle you need to pay more attention and since youre paying attention make call outs for your team