hey i was jast serfing for guitar stafs and i read your Q... For good and fast strumming try practicing with out the guitar first! Relax your hand (Palm&fingers) and shake the hole thin up and down as fast as you can for a few seconts,(Jast to warm up) then take the guitar,with the Left hand mute all the strings so you do not wake every one up and by still shaking the right hand "slowly" bring it close to the "muted" strings.( if you play a steel guitar i ton sugest you try that. And onece you get an nice smouth sount try it on chords!jast relax the wrist and shake it! ;) happy playing!