Driving to riding?

My horse is a carriage horse, and as far as I know, she has been her entire life. I can ride her just fine, but she doesn't respond to traditional riding cues. I can ride her around bareback in a halter and leadrope and get her to go whereever I want her to, but I'd really like to train her to respond to my leg and to get her to canter.

I can get her to walk and trot fine with my voice, but she won't canter at all. I never canter her when I'm driving her, so she doesn't know any voice commands for that gait. How would I go about teaching it to her?

If it matters at all, she's a Percheron (maybe TB cross?), about 16 years old, and is very calm and will do whatever you want her to as long as she knows what it is that you want her to do, obviously.

Try lunging her and get her to canter. If you have a riding arena or vacant paddock then I would suggest freelunging first, (lunge her but without the lunge line) and get her to canter that way, you may have to chase her around a bit first haha. :)

Pick a distinct voice command for him to canter such as Git or Hepp.

Thanks, I'll try that!

Along with lunging her, you should try long-lining her. Before we ride any of out horses, they are long-lined extensively when they are young and know all of their voice cues before anyone even sits on their back.
Pick the cue that you want for her canter (we turn our horses heads slightly to the rail and use outside leg and say "canter"). Keep practicing that on the long-lines, and that will simulate riding because you will have "reins" and keep all of your cues very consistent. Our fully equitated horses know "canter left lead" and "canter right lead", you don't have you use any leg or rein on them, they do it all by voice.

You'll have to teach her to respond to riding cues like you would an untrained horse. Gradually increase the pressure (squeeze, bump, spank, ect) until she picks up a canter and then release all of the pressure as her reward. At first don't force her to stay in the canter because she'll only get frustrated and won't know what you want. But don't worry once she understands your cue to canter you can keep her going.

It also helps to ride with your energy. When you want to go faster bring your energy up as well and vice versa.

And once she understands the cues then work on the correct lead. It's a lot easier to learn in a round pen because most of the time they will pick up the correct lead on their own.

Go back to the beginning as though she is an unbroken youngster. She will progress much faster than those since she already knows so many cues from driving. Start of working her in hand and teach her to move off pressure, yield hq, turn on forehand and haunches, side pass, back up (she should know this if she is driving). Then progress to the lunging and learning the voice command for canter.