bhop + double jumps

Well ive been playing GM for ages now and feel its time i properly learnt to bhop as i see some people do it all the time and they own as BL, however i've read up (and watched videos) on how to bhop and also double jump, but when i go to do them i cant seem to do them right or are always visible.

Can anyone suggest what i'm doing wrong? am i doing things too slow/fast etc?