Amumu is a nice champion that fits into many teamcomps. He is relatively easy to play, suitable for lower ranked players to climb. While being able to completely change a game if he lands a good combo, he can make a big difference even if you don't find a good opportunity. For this build, it is better to bait objectives like Baron and Dragon, and initiate team fights there. It is harder to fight in the jungle because you can't use ur ult to it's full potential, so flanking would be the best idea.

Either go straight into their team, or flank from the side. Either way, simply Q --> protobelt into their team--> epic ult. you can also flash after bandage toss if the enemy team is too far away. Simply aim for the enemy team squishes in teamfight and burst them down.

Doesn't really matter which side you start as long as it's bot(better leash). If start red, skip wolves and go straight to blue. People would tell you to skip raptors and go straight to red, but since amumu's e have dmg reduction and lowers cooldown from attacks, you can clear it pretty easily. Make sure to smite red for the health. If you're healthy, go krugs. if not, go scuttle then krugs. Afterwards, u can't gank mid/bot or back, depending on which is easier.

Amumu has pretty good early game dmg from his bandage toss and E because of it's base dmg, and you can fight most champions in the jungle. So if no lanes are missing, you are pretty much free to invade the enemy jungle.

If possible, don't be haste on using your bandage toss. If you have ult, try to lang it first to guarantee your Q to land without fail. Even if you don't, try to push the enemy towards the wall and force them to walk straight, making it easier to land your skillshots.

It's pretty easy to farm with Amumu, especially when you're going ap. Simply clear the small ones with your W and E then bandage toss the big one. It is best not to use your W if you don't have blue or have less than half mana. Refrain from using it after first clear. For the first clear, you would have enough if you use your skills properly, so it isn't a problem to use your W. Just make sure to turn off your W if your not jungling or fighting someone.