Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
1- Start Gromp no matter what (Blue Side) all the time since you use so much Mana
2- Blue so you regenerate your mana. Also spam your E
3- Do the Wolfs so you get lvl 3
4- After crab you have enough HP to gank so..
5- Gank Mid or Bot so you can get a good early game
What you do now with your Items
After you got your Jungle item completely enchanted it should be way easier for you to clear the Camps.. You should Now proceed to get Lichbane for more Movespeed, Mana, and One-Shot potential with the Spellblade burst combined with Q or Auto-Hits. You also could directly go for a Rabadons if you are so fed already, don't forget The Void Staff.
For boots you could go with Cooldown or Penetration its up to you..
With this build i haven't lost a game yet
For your Combo.. you have to get your Passive on someone With a W - Trap (Bushwack) or With your Q - Spear (Javelin Toss) then you Change your form R - Aspect of the Cougar. You then proceed to W - Pounce on you can try to use your E - Swipe while you do this, your Q - Takedown should... take them down :D .
If you get Low or your enemy is still alive use Q - Javelin Toss or E - Primal Surge to get Some HP back and also deal Damage again.. IF you hit the Second spear you can Use your combo again and again since you dont use mana in your cougar form..
Have fun and i Hope i helped you