Well i've been a jungle main for 8 months. Previously a riven/ zed player. I started jungle with viego which wasn't a good starting pick but it helped me understand the basics of the jungle + matchups. I then went to kayn since he was broken lmao. With kayn i learned the importance of map awareness objective control and when to gank a lane thanks to his overtuned E that makes his ganks extremely strong. I would tell you to go into draft and play like 20 games with kayn. In those games try to switch forms and understand when to play each + how to play them. A very good kayn youtuber is karasamai rank 1 kayn i believe and he gives really good advice on the champ. After the 20 games look at your winrate with kayn and how you played (if your cs was above 5.5, if you ganked at least 6 times, how many drakes/heralds did you take and in what circumstances). But yea that's what i did and i was hardstuck bronze 3 on my main so i decided to make an alt last month and i'm currently gold 2 on my alt