If you want to practice your canter my advice is riding on a lunge line. Have your trainer of someone else lunge the horse while it is in a canter. Then you can focus more on how you ride and the motion of your horse. Also, it may be a little easier to control your horse. Going in a circle also helps.
-You can do a spiral. Put your horse on a circle and make her slowly go in to make a smaller circle and then out, like a spiral. You can try it with her head in and her head out.
-you can do a serpientine. Set up a line of poles down the middle of your arena like
And then kinda like a snake, weave through all the poles.
-and then you can also set up a jump and then bend your horse from the left to the right after ever canter step.
One thing my trainer had me do was make her side pass around in a circle. It's hard to explain but go in a circle (about 15 meters) and use your inside leg to move him over in an arch so his hind feet move more than his front. Do this both ways a couple of times. That really helped my horse loosen up at all gates.