I fish the soft-hackle across and downstream, mending to avoid drag, and then let it swing at the end of the drift. I typically retrieve the fly upstream in short 2-3 inch strips for a few yards after it swings acroos the stream. For the record, I prefer a thorax of brown fur on the Partridge/Orange soft hackle wet fly (I like to think that the trout prefer it also). This fly (and other soft-hackles) with the above and similar techniques has balied me out numerous times.
There are several books on the soft-hackle by Sylvester Nemes, and the technique of Jim Liesenring (Liesenring Lift) is covered in his book "The Art of Tying the Wet Fly and Fishing the Flymph".
A short description of the technique is described on the linke below:
Frontrangeanglers.com - The Leisenring Lift