Haven’t played in 2 years and suddenly love jungle.

Hello, I have a few general questions as I haven’t played in 2 years, and never played jungle in the past (support/enchanter main lols) but now I actually really enjoy the role.

1) which champs should I play to begin with? I’m currently playing Amumu however when he’s taken I’m so stuck, I was thinking sejuani but not sure about the impact I’d be able to make/carriability in solo queue. 2) is it worth reviewing my own VODs if I’m not very good? For example I only ever peaked gold whilst being a support player. 3) I always prioritise thise 3 midget things before any other objective in the game - is this okay to do?

Anyways, sorry if this clutters the subreddit! I’m really enjoying jungle atm and thought this would be the perfect place to ask for tips :)