You’re gonna want padding on the shins and under the shoulders for comfort, getting a belt and looping elastic with a buckle connected to the thighs should keep them up, more elastic from the shoulders into the chest should also work well
As in it's difficult to put it on without help from another person or you're having trouble getting it to stay in place? If you're having trouble getting it to stay on, what fasteners are you using? Velcro, Magnets, Snaps, Etc.