Start running forward jump and press crouch and space when you reach ground and start bhopping. You'll be completely invisible after three bhops when front bhopping. Read my tutorial 'Making bunnyhop easier' in tutorials section.
Alternatively you can start normal bhop (backwards one) and move your cursor in the direction your going and you'll start front bhopping. This is useful when you are surrounded by GR or don't have much space to run forward.