Till LvL 6 you should go for a more Warwick based playstile. That means should jungle till lvl 6 then go for ganks with your Ult. You Ult is easiest to use on mid cause you are not supposed to move much in different directions. Your ult is best used while you are near the 2nd tower of the lane , cause you get the extra DMG from your ult after you ran a certain amount of space.

After The Early ended and your team starts to group up YOU are the one having to engage . You Ult is the best way to do it . If one of the carries is standin in front you shall not be afraid to all in with your Ult cause your Ult+Q combo offers alot of cc.

Early Ganks are much more difficult to perform you have to get a feelin when your Q is ready to knockup cause your Q CAN knockup if not fully charged ,therefor you have to get a feeling for it.

Counter Jungling is a bit tricky with Sion , You Q offers alot of dmg when used correctly therefor you have to ward certain bushes like Under the red on Blue Site . Also you lack abit on trading with certain champs like Vi , Amumu , Zac or Maokai

Sion works well with champs like Veigar cause of his massive AoE Stun , Leona cause of the same reason and Morgana

Knowing your Ultimate is Really important . Your ult Ignores EVERY Crowd Control. Here are some interactions with certain CC . Vi Ult: if you run away from Vi´s Ultimate she WILL catch up to you and do the DMG but will throw you up and cc you , she will just stand where she catched up to you. Azir Ult: Azi´s ult is his own wall like Anivia´s W and Trundle´s E therefor you will get stunned and pushed back if you run up to it but will do the AoE DMG at that point.