"Farm [ the specifics of which are subject to your champion matchup(s) and tend to border on balance of the following], know when to take what objectives, keep an eye on death timers, ward chokepoints, know when to ward offensively and defensively, position in a way that predicts the enemy, know how and when to harass who and when, trade with enemy cooldowns, capitalize on item spikes, feel free to tilt the enemy jungler through shenanigans safely, click the enemy to keep track of their health when needed and know your own damage, keep track of mana and manage it, roaming effectively and actually roaming, know how to path as a jungler and predict the enemy jungler, countergank based on knowledge or counterjungle based on last seen gank, teleport wisely, itemize dynamically, know when to split and when not to, know how to position more effectively in a fight or before one, know when to intercept baron or dragon, know how to rotate and tell your team so, be mechanically proficient enough to outplay 3 man dives with at least 1 kill (in most circumstances), etc." All sound advice from my view.