What kind of flexibility you seek,overall or...
This program is the best and it works,i do 2-3sets+quadriceps stretching with it,because this program will stretch hamstrings and hips excelent and that way you can stretch opossite muscles easyer.My brother needed 10inches to touch his toes and in 1week he could touch floor with all 5.hand fingers.
3-Minute Flexibility Routine - Men's Health
Here is another program,but read it only if you are realy comited to this sport.
Step One
EDIT:
End for squats i have a tip for you,before training sit down deep as you can(like in squat but without bar).Try to hold your coordination for 5minutes not geting up,go deeper and deeper,SOMETHIMES LIFT YOUR HANDS UP LIKE YOU'RE DOING OVERHEAD SQUAT POSITION(THIS WILL STRETCH BACK),somethimes try to straighten your back because they are bend,and try not to fall down due to that,than you can take dumbbell and hold it with hands up front.Don't lift your self on toes when you squat,fool feat on the floor.
With time you will flex your gluteus and be able do squats without problams.
I hope i help.
