Before this thread spirals off into a spur debate, I would like to attempt to help the OP. I would say try what you can without spurs or a crop before you use them, there is nothing wrong with choosing to ride with or without them.
I'm going to choose to help with the left lead first, just because it is easier to explain if you choose a side.
For the left lead canter, the first beat is the right hind. To get this first step, your right leg must be behind the girth and give a sharp squeeze with your heel. You may also want to position your right seat bone back more to help exaggerate this signal. You must sit deep into the movement, not posting. Lean back slightly to the right and relax yourself, you do not want to be tense in your back. Think of allowing the energy of the hind at the canter to flow through you. If it helps, you can say "canter" or use a vocal cue that your horse recognizes as the canter command on the lunge line. To make things easier, you can try cutting across the arena like you are going to hit the wall, then immediately before the wall turn to the left and ask for the canter. This act helps to dislodge the shoulders which can make cantering easier. If he doesn't canter immediately, keep the pace (not letting him get rushy) and keep asking with a stronger outside cue every time. Do not let him run away at the trot if you ask him to canter, slow him down and try again and each time make your cues stronger. It is important for cantering that you have a nice balanced trot or walk before the canter depart. The trot/walk before the canter should have energy but not rushed, it is not possible to get a running start into a good canter.
Back to the spurs and whips, I would personally try a dressage whip before you try spurs because it is harder to get used to using spurs than a whip. If you choose to use a dressage whip, use it with the outside leg (for the left lead, you would have it on your right side and tap his hind immediately after your leg cue if he does not canter with your leg).