Hip range of motion and the limitations it...

I have a pretty limited range of motion in terms of splits in my hips. I'm pretty good as far as bringing the knee up to the shoulder. I can almost get my ankle behind my head. I have a really bad range of motion when it comes to things like side kicks and arm bars from gaurd. So, I guess what I'm asking for is some tips on building serious hip mobility and range of motion. I want that effortless type of movement. I know that genetically I may not have the "gift" but I know I can be better than I am. Any tips or references will be appriciated.