If Cheyenne has done it, then yu need to work on yourself mostly.
What I would suggest doing is loping up to the barrel, then brekaing down in gaits to a trot for the circle. You could start at the walk too, but I like doing trot/lope so long as you can do it fine.
When you go into the turn, you should sit back against the saddle and relax yourself. Keep the curve in Cheyenne's body and let her follow her nose around the barrel. You may have to grab the horn once you get more speed, but at the slow gaits you shouldn't have to.
After you can lope/trot the pattern, pick up a continuous lope and try it. Now here, ask for the horse to collect and get in the ground to turn by sitting back LOOK LOOK LOOK at the next barrel before you even come out of the turn. Then lean forward more on the flat stretches going into/out of the turn. Remember that sitting back is part of the turn signal to turn. Really give her head when you're on the flat.
I rarely ever set up the pattern though. I may set up three barrels in a straight line, four in a square, two on the diagonal, etc. However, when I do work on the pattern I do a lote of rate rate and RATE! Really make sure the hors eknows to collect and then drive out of the turn.
An random excersize I do a lot is lope (Not run) at the barrel and then use my inside rein/leg to pick up my horse and move them off the turn if they start diving in too sharp.
Also, on that note, I would practice loping twenty feet circles, then ten feet, then five feet, then ask for a barrel turn. If I have a horse that dives in, I do that excersize a lot. Of if they anticipate the turn I push them right past the barrel and keep doing it untilt hey relax.
Now, if your hrose gets antsy (Which I hate) I will throw a show to walk the patern calmly if I have to. Always take a break from running and just calmly walk around. If they get super chargy on the turn I stop and make them circle it until they relax, then walk them out of the turn.
Just a few tips that I use. I really, really loath antsy, stupid, bawking, chargy, run-right-through-your-hands barrel horses. I don't mind if they're hot and happy to do their job, but I don't want a jittery mess going into the alley.
Hope this helps. If you ahve any questions, let me know.
Pssh.I didn't pick up the wrong lead
It's called a counter canter...
...A very advanced maneuver.