#bikenite A5: Changing tyres tips? Change 'em for Schwalbe Marathon Plus.
I mean, the other thing is, always partly inflate the tube inside the tyre so it doesn't get caught under the bead.
Also I always inflate the tube until the bead seats, check the bead all 'round and make sure there's no pinches, then let the tube down to 5psi or so and bounce it a few times to let it 'relax' any stretched bits and then reinflate to pressure. I have no idea if this is just a superstition or not :-)
As for kit, I just have two flat plastic levers which are nice and slippery for sliding sideways and a hook-shaped steel one which is good for getting that last bit flipped over on really stubborn tyres. I've seen a few people recommend a spring clamp as well to push the beads in on the opposite side, I might add that to the kit and try it next time.