My technique is similar to yours in that I back pedal for the hub gears and back off the pressure for the "derailleur" gears but I do pedal forward lightly to make the the "derailleur" shift. My question just involves having to double press the derailleur. I suppose it would make the shift in one press if I press it all the way down and hold it there until it shifts, as Joe Remi suggests. Is that really the nature of the beast? I don't think I was doing that when I first got the bike.