I practice on the wobble boards at the gym. There is one which is hard and one which is very hard. They are particularly good for ankle proprioception. I was totally rubbish for many years until I started to get treatment to tighten my ankles and now I am steadily progressing. I balance on one leg and two legs and recently as I have improved a lot, do mini-squats on the less hard of the two wobble boards. I do it with trainers on as that is how I spend my day! You can also go round in a controlled circle.
Start really easy by gentley touching something to help with balance or have a stick in one hand on the floor again to help balance originally.
But if your ankles and feet are very lax, as mine used to be, and more lax than the health professional has seen before, then the wobble board will be too much.
Joint group leader for South Central (Bucks, Oxon, Herts)