Lead Help!!!

Have you ever played stick horse? If not, stop what you're doing, get up from the computer and canter around the house like the horse breed of your choice. When you do that you'll notice one of your legs tends to lead. Now skip a step and swap leading legs.  That's a flying lead.  Now watch a cantering horse. One of his legs leads. When you're in the saddle you really have to figure it out - maybe if someone is on the ground telling you so you know without guessing.  You learn to feel that stuff. And be sure when you're in the saddle your head isn't all leaning over. Cuz it's heavy.... fat head JUST KIDDING! We're all fat heads... But seriously your horse can feel the shift in weight. So sit up straight and maybe cut your eyes down and check out the difference in the shoulder movement...  []
 
eta: right lead, left lead, wrong lead... The leg towards the inside of the circle should be leading.

Normally I lean over and check lol but usually to get my horse in the right lead I trot him in a tight circle and apply some pressure on the outside with my leg and pick up the inside rein while asking him to canter and he instantly goes into the right lead then I take him around the arena and repeat the process for the other lead. This really helped my lead confused horse to learn to pick up the right lead the first time.
What Hunter said is true, it's the front leg that strikes out first in the canter or lope. 
Good Luck!