Teaching her to disengage her body parts to pressure
Changing directions on the lunge without you having to stop and reposition her
Have her walk over small obstacles and scary objects
Have her walk politely, changing direction, gait and back up when you do (so if you speed up, she should start trotting without you yanking on her, she should stop when you stop, back up when you do, etc)
Look up some videos or buy them or rent them.
"Gaining Respect and Control on the Ground" by Clinton Anderson is pretty good, and I think there's youtube snippets
"Roundpenning for Respect" by Clinton Anderson is also handy
Try looking on google and youtube for 'groundwork exercises'