One thing that every cross country course has in common, no matter what the level, is that the first jump on course will be negotiated from at least somewhat of a standing start. And you have to be able to do it WELL, if you want to have a good first jump! Every rider should be working on this!
"The quality of a good canter: round, energetic, straight, cadenced, light. You have to feel in the strike off that the horse lifts his forehand without throwing himself forward." ~ Nuno Oliveira
To keep your horse straight in the canter, always be thinking of a slight shoulder fore positioning.
The inside rein is like the directional in your car. You use it to indicate the direction that you plan to go, but not to actually turn your car.
"You need to have a good seat to be able to use a spur correctly. You should not use them unless your horse is in front of your leg. They are not to be used to get your horse forward." ~ Hazel Roberts