Don't soak prior to a shed. It actually has the opposite effect of what you intended it to do. Soaking washes away the natural lubricant that the snake needs in order to shed properly. Just keep humidity where it needs to be and you shouldn't have shedding issues going forward.
There's a link in my signature about setting up a glass aquarium that gives good recommendations for screen tops. Partially covering it with foil/plexiglass is usually a good solution.