There are many talented Jungler in Worlds 2020, however, you can not follow and learn all of their skill. It is hard to become a pro-Jungler, but, at least, if you master these skills, you will enhance your play style.
For every Jungle Champion, if you learn by heart their skills, you can find the fastest way to farm that cost less HP. For example, SofM is one of the best Lee Sin player in the world, he can clear every camp at a scary speed. He farm so fast that many players tried to catch him but can not break his 2 mins 47 secs record. (You can read more about SofM records here). Moreover, if you master a Jungle Champion, you will counter it easily when enemy pick your Champ.
At last but not least, timing the respawning time of camps helps you gain more exp and gold, you will overcome enemy easily.
Control the vision, control the pace of the game.
If you have enough vision, you can have more advantage than enemy, your teammates can make use of your wards in order to gank or counter gank, steal camps or objectives. A helpful tip is that you can hunt for enemy wards and farm them, these wards also give you exp and gold as much as a creep. Destroying enemies wards is reducing enemies vision, it is really helpful for all of your team, you can make easy gank or help teammate in poking enemy, help your team Laing phase better.
Using information effectively
There is a fact that, if a enemy show up in your team’s vision, you can know his items, his CS and Vision Score on the Scoreboard. And with these information, especially CS, you can guess which camp was cleared by enemy Jungler, so that you can draw the path of him then decide to hunt him or steal his camps.
You must learn how to steal or defense your objective against enemy. For example, if you are playing Lee Sin, you can use your ultimate to push enemy away then use Smite to steal Dragon or Baron. Or using Lilting Lullaby (R) of Lillia to make enemy ‘go to bed’ then secure your objectives.
Help teammates at the right time
With every Jungler, it is not true that every gank must lead to kills. Sometimes, just poking or making pressure, warding, pushing is as effective as a kill gank. For example, if your teammate is recalling, you can hold the minion wave so that when your teammate comeback, he can still have a safe position, you will also have a lot more exp from Lane.