I approach the jump at a walk. Obviously, if your going to do this, practice with a tiny jump. Walk her over it, just like it's a trotting pole. After your happy, walk around the arena. Turn her towards the jump, a few strides before, trot. She'll probably go quite slow, so won't bolt. Also, putting trot poles before the jump makes her think a bit more.
Also, try combinations. Put two jumps in front on each other and trot her over them. She'll have to focus more on the striding. Make sure you put a trot pole after the last jump so she won't bolt.
Or you could just try cantering her or trotting a circle just before the jump to get the speed YOU want. Posted via Mobile Device