Need some tips to get flexible for wrestling?

i had this problem in high school.i'm on a greco roman team now and my flexibility is honorable.my biggest concerns are my hamstrings, hips, and back. i'm surprisingly a really good runner. but i get sore really easily and i'm having a hard time with some of the throws i learn in wrestling because of my flexibility. anyone got any tips or know of any supplements to help out with this?