can i please have advice on rengar? and clarification

so when i play rengar i dont alway do good. ive played him twice after the 6.2 nerf(?) his late game burst is down but early game damage is up which i like alot. but thts not why im posting. usually my damage is really low in terms of total champion damage. is tht normal for rengar? or am i playing him wrong. (probably) i am bronze thankyou for the advice. oh, and for strategy what is the best way to play him? split pushing and then coming into a teamfight late (or getting a tower) or always staying near team. explain is teamfighting for me plz. ik as much as destroy the adc and try not to die.