Start SLOW and Practice, Patience and Practice! WALK the pattern & when your horse is doing good at the turns, move up to a TROT. Do the same thing....when you are happy with her turning (remember to use your legs as cues!! Some folks even use a verbal cue like "Hup" or yell something else) then move up to a lope or a slow gallop. Once you are satisfied, go faster. Just don't get her bored with the pattern; (doing it over and over and over) keep it 'fun'. Good Luck! Just remember the PATIENCE!! It's easier to teach her correctly the first time, than to have to re-do or unlearn!