Jungling problems

Hello, I'm a Katarina main and I recently decided to pick up Lee Sin. The problem is that I don't really know how to jungle. Yeah it's sad. My first problem is that jungle camps do a lot of damage to me even if I kite them. After that I'm left with almost no health. So I was wondering if you guys could give me tips about avoiding these problems.

Please don't call me a noob I'm new to the jungle. PLS ANSWER