That is, do a movement, look expectantly at the client, and let her do it. Then do another movement. If she has trouble getting a movement, repeat it, or break the components down and practice those. It might work well to use a certain object you move and then ask the client to duplicate the motion and path of that object. Like, hold a pen or a book, make movements, circles, lines, etc. with it, and then hand it to the client and ask her to repeat the same sequence of motions.
Linear motions are much easier to duplicate than curved ones.
Start with simple hand movements. Then move around and do whole body stuff. Also facial expressions. Start very easy and only gradually make it more and more challenging. Client should act like a picture in a mirror, moving at the same time.