No – any will do. But pick one that is made of very thin rope – the thinner and stiffer the rope, the bigger the “bite”. So remember that – the yanking that you do with a flat, nylon halter will be magnified many times when using a thin, stiff rope halter.
And you might try switching to a dressage whip rather than a crop for several reasons, one of which is it is longer and so therefore a better extension of your arm, which is what it’s suppose to be anyway.
BE SURE that each time you have to whack her with the whip/crop, you lower your energy to a state of calm immediately afterwards, and follow up the whack with rubbing her all over with the whip in a friendly way. She shouldn’t EVER think the whip is a bad thing or become afraid of it.
You need to start transitioning from correcting her to DI-recting her – does that make sense?
So – as an example – to teach her to move back: start by facing her and her being about 6-7 feet away (get yourself a nice 9ft. rope lead rope as well). Start asking her to back by just wiggling the rope so the halter bounces again her nose. If you need to, you can increase the pressure. If that doesn’t work, you can “march” towards her. REALLY bring your energy up – literally march towards her – lifting your knees up high, chest back, elbows pumping – act like you are going to march right through her!!
Then, AS SOON as she even starts to lean back, STOP. IMMEDIATELY. Return your energy to quiet and calm, let the rope stop it’s motion and make sure ZERO pressure in on the halter. Praise her.
Rinse, repeat. Each time you can ask for another step.
It’s sort of hard to explain in writing, because it is all about timing, energy and release.
And remember to mix in plenty of loving strokes with hand/whip. You are not trying to make her afraid of you – just respect you.
The whip/crop should only be used as a final resort – your body language and energy should be the main “tool.”
Buck Brannaman has what he calls his “little red book” which explains all about basic ground work. It’s available on his website for $20 or you might get it from Amazon for less.
It will pay for itself over and over again, believe me…
Again, good luck – sounds like you are making progress – just don’t go overboard now with the whacking.