Not sure what rank you are, but if you're Gold or lower I recommend just learning Amumu jungle (or AP Malphite jungle, which seems to work for me, but feels questionable). It's pretty straight forward: ignore your laners desperate cries for attention (you: Level 3, half health, killing bot scuttle; your top lane: PING PING PING PING PING PING PING PING PING PING PING PING PING), clear camps, rush to 6, kill someone with ult, take an objective, go back to jungle for two minutes, repeat. You'll be pretty effective with that relatively straight forward, low complexity gameplan and from there you can learn to weave in efficient/effective non-ult ganks, invading, optimal routing, surviving the asshole Lee Sin who really wants your dick, etc.
From there you can pick up more complex stuff, but something with a simple play pattern will help you focus on learning the nuance of jungle.