How do u do a Flat spin?
On most of the airplane I have flown I've found that the way you enter the initial spin does not make much of a difference...If it won't go into a spin from any attitude, the airplane is not going to flat spin anyway.
I guess it would be better to start the spin nose down so it's falling vertically instead of moving forard a little, so stalling it out first would be better....
You just gotta try everything!