The slow approach is a good one, just using enough power to get rolling, then slowly, very slowly increasing power. However, I would avoid leaving the ground before you've worked up to a reasonable power level, enough to climb under normal conditions anyway. Given the fact that most models these days are way over powered, you really don't need full throttle to climb out, that's for sure. You really just need enough power to sustain a good rate of climb with out getting close to a stall.

Personally, while I know the full power and pray method works for some guys, I really worry about that approach. It will work for lightly loaded planes with lots of power, but it's horrible practice for planes with a heavier wingloading. The biggest danger is leaping in to the air on just the engine, with out enough airspeed. The resulting stall and wing drop can lead to a nasty cartwheel.