[sc_rufctr]

No trick really... Just practice.

When you get to tire mostly on check that both beads of the side that's in are is in the middle of the wheel and not on the edges.
Pinch the tire with you fingers and push it inwards towards the final bit your trying to get on. Continue working upwards on both sides towards that final bit and then gently try and roll on that last bit.

By doing it this way you're trying to give that final part a bit more slack so it goes on easier.
If the beads are in their final position on the outside of the rim you'll have the least amount of slack at the final bit.

Also put a little air in the tube to stop it getting pinched.

I hope that makes sens.