Give me hip moves!

In the summer I had a knee injury which led to me unable to do nearly anything for a month and a half. After surgery I started physiotherapy and I started going to gym for the first time in my life. (About two months ago, woop)

Ive been going for three times a week and managed to strenghten my leg a lot. The knee has almost recovered full movability but some moves just wouldnt work and caused pain. Turns out that during the phase when I couldnt move much, my HIPS got stiff and its causing problems with a lot of things, including learning to run again.

Give me ideas how to stretch/ warm up/ strenghten hips best! Thanks!