nothing wrong with the tips above... but instead of focusing on body parts.
watch this -
how is his FH different from yours?
here is a hint - what is he trying to swing? that Wilson in his hand? or the entire unit that's made up of the upper arm, forearm, and the wilson? (what I call the 'human racket', as opposed to the Wilson -the 'graphite racket')
now envision the same picture when you practice.