I was alwas taught to bring to motor up to full power for 20-30 seconds. This creates airflow & also ensures your motor can make full power (better to find out it can't whilst still on the ground).
Arms out straight to the sides & lines tight (to prevent any chance of them being sucked into prop - as already stated)
Come off power, commit, run, move under the center of the wing (by feeling what it's doing), nail the power & run as hard as you can.
The only thing I found that works differently for me is that the tips on my Synth sometimes seem a bit reluctant to inflate. I got aorund this by laying my wing out straight (not in a horseshoe), it's working well so far. Synths also seem to need a fair bit of pressure on the A's, otherwise they can hang back a fair bit.