As amumu, Try to power farm to level 6. This will help you unlock your Ultimate y quickly and allow you to start ganking your lanes.

Whenever your Ultimate y is up, you should try to gank a lane. Every Ultimate y use should result in a kill. Try to gank as soon as your Ultimate y comes off cooldown.

After successfully ganking the bottom lane, make the call to take the Dragon. Getting all the Dragons will give you an early soul and deny the enemy a variety of buffs. As amumu, Try to feed the farm to level 6. This will help you unblock your Ultimate there quickly and will allow you to start inflating your tracks. Every time your Ultimate is up there, you should try to inflate a way. Each Ultimate use should lead to a murder there. Try to inflate as soon as your Ultimate comes out of cooldown. After successfully inflating the lower lane, make the call to take the Dragon. Getting all Dragons will give you an early soul and deny the enemy a variety of buffs.