i second WD-40, works like a treat. take off you air filter and glow plug after you have finished running for the day and spray a one second burst in both the carb and cylinder.
turn the engine over for around 5 seconds (i usually pull the starter cord 10 times), then repeat once more.
when you have finished, turn the model upside down and spin the engine over to get any excess WD-40 out (you only need a film on all the internals). also tilt the model so that excess runs out the exhaust pipe. last thing you want is a pool of wd-40 in the engine.

i found this technique makes the engine easier to start next time, since you have less WD-40 to flood the plug.

in my experience, after run oil makes starting next time a right PITA.

oh yeah, i am assuming that you have run the engine dry before doing the above.