Tips on strengthening the right lead?

I have a 20yo OTTB mare. She's had a year of off the track training (even though she's 20. After racing, she was a broodmare for the rest of her life), so she picks up both leads and is comfortable cantering on the right lead for the most part. Her trot and canter to the left are very balanced and she has a wonderful hunter frame. To the right, she goes on the bit, but picks her head back up every few strides. At the canter, her butt is to the inside, and she likes to lean a bit (not horrible though). She can be dead to my right leg, so we've been doing lots of turns on the forehand and leg yields, and it's getting better. Anyway, she just started doing rated hunter shows this year (doing wonderful!), but one thing I want to improve a lot is her right lead canter. I have a trainer, and she wants me to do lots of small circles at the canter to improve her balance. I was just wondering if you guys had any other tips for me! Thanks!