I need tips about kicking

[Fish]

I'm struggling with my kicks as well, especially roundhouse and side kick.

 

Can't seem to straighten my leg out fully on side kick.

 

Roundhouse kick height has improved with some stretching (I've gone from waist height to chest height in around 3 months). It's painful though. I guess I'm too tight.

 

As well as giving the types of stretches that might be useful, it would be good to describe them or perhaps link to another page or website that does.