I think my biggest problem is that in a recent effort to fix my general posture, I took the ‘chest up to get shoulders back’ route. This has obviously led to me spending a lot of time in extension. My hammies are very tight so I am constantly working on them to relieve some tension. The biggest help though has been to screw the feet and butt and get the knees out. Its still requires concentration to maintain position and Im still not sure how I go rep to rep but I think if I keep practicing I’ll get there. 

Thanks again for your help everyone.