first you have to know where you start if your bot lane is easy to gank start from top side for example:Your bot lane are Jhin and Blitzcrank and your top laner is nasus and you are in the blue team, start from top side and take your blue buff nasus can't help you too much because he is too weak so you will take your blue buff and wolfs with low hp,then go bot side jungle and open your w and just spread your poison from your jungle item it heals you and you can take your red buff and your hp will be full then try to gank mid or bot if you against a early champ jungler you can gave him bottom side scoutle and you can go for top scoutle you can easyly clear your jungler when you reach level 6 you will see amumu's real power

now you are about 10-12 level and you have very good damage you can easyly hit your ult 3-4 person in tf just try to hit your q to their carry and tap r it will be easy team fight

-you can ult then flash(cancel animation) for no reaction time for your enemy
-e flash(cancel animation)
-q flash(cancel animation but you have to be really fast because this one is hard)
-your passive is deal %10 more true damage to your enemy when u go for fight first auto attack him then use your skilss