If you play Rek'Sai "jungle supp", your main role is to gank as much as you can ( also farm ). Your ganks are much better after you buy Stalker's Blade. You want to gave all the kills to your team, even to the tank, because your items are really cheap. You buy the Locket so you want to stay in teamfight everytime when it is one. Don't forget to use your actives. You must focus the objective and allways knock up the enemy carry, even two times in a teamfigh if you can. You want to deny enemy vision and you can take the Sweeping Lens at level 1 if you want to gank early. Also I prefer to start at the Krugs and smite them. At lower levels I use W multiple times so I recive HP and knock monsters and get free AA on them.