First of all, you shouldn't neglect your right side whilst strengthening your left. Achieving all over body/lower body strength is more practical. I recommend that you start of doing squats as this will help strengthen your lower body muscles along with your hip flexors. The link below will show you how to perform these safely. You can also progress to using weights to make this harder. For this exercise, do 10-12 squats, rest for 30-60 seconds and repeat another two more times.http://www.youtube.com/watch?v=Up_48p-BMug
I would also recommend that you do Bulgarian split squats. This will have you working each leg individually and therefore building up more individual leg strength. Again, the link below shows you how to do this exercise. For this exercise however, you should do 10-12 Bulgarian split squats on your right leg, and 12-14 on your left. The extra two reps on your left leg will help it catch up with your right leg. Again, rest for 30-60 seconds after you worked both legs and repeat the exercise another two more times.http://www.youtube.com/watch?v=tmkKqMDupLU&feature=related
If the links don't work, just go on youtube and search bodweight squats and Bulgarian split squats.
Hope this helps