Join Date: Jul 2008
Location: between florida and maryland, usa.
it helps to get an idea into your head, but ultimately, lots of strength and work will do it. Try your best to sit the fence, but push your legs forward. So that way the horse will push you out of the saddle and you won't resort to overjumping. Also, make sure you're not pinching with your knee. That can be a big cause for your leg to slide back.
But for me, it helped to basically think... 'push your heels towards his nose and try to sit as you feel the take off.' you'll have to do it a lot, but eventually, you'll be gain some strength in your leg to hold the position.
Also, a lot of core strengthening. Have a friend throw you on a lunge line. No stirrups, no reins, etc. if you feel balanced enough, maybe even try some two point with no stirrups or reins. You want your body to be able to hold it's own over the fences, so gotta get those muscles strong!
Hope that helped! :)