I have to cope with numerous periods of off time because my medication includes Entacapone. Walking is very difficult and I have to grab door frames, furniture etc. Recently I found a technique that is of help. I grab a piece of black cable that is about 18 inches long, hold it at each end, and holding it horizontally in the lower part of my field of view. It acts as a visual cue. I straighten up, and can walk forwards reasonably well. Quite a splendid feeling.
It might work for other people.