My smash is quite inconsistent and i was wondering if someone could help me by giving me a few tips. I use differnt techniques alot which I dont think is a good idea. I would prefer to use 1 technique all the time. THANKS.

A consistent smash is founded upon a consistent clear.

When you can do 50 baseline-to-basline clears without one of them falling short (as in not shorter than doubles rear service line), you won't have any problems producing consistent smashes.