I made a pair of boots for my boyfriend's
Luke Bespin costume a few months ago.
I adapted a pair of suede look slippers, bought some suede to match it, and turned them into these:
The suede colours didn't match exactly, so my boyfriend got some dirt to try to blend the two together, and it worked pretty well.
The pattern shapes I used look like this:
The straps are just strips of suede, with rounded edges and velcro to keep them attached. Although if I had more time, I would have tried to attach them to the back, so that they don't slide down. Otherwise you have to put them on really tight, so they don't wriggle down. We were hard pressed for time and didn't get a chance to do that.
They were fiddly, but otherwise relatively easy to make. The most difficult part we found was glueing the suede around the slipper.
Good luck making your boots. I hope it goes well