Removing wallpaper can be a difficult process on it's own, but removing wallpaper that's been painted over is an even harder task. Major physical labor is involved, but there are steps you can take to accomplish this on your own.
Lay a sheet of plastic on the floor to catch the painted wallpaper that's been scraped off. If you're using a chemical stripper, lay towels down to absorb the dripping solution.
Penetrate the paint film by using a stiff wire brush to wear down the surface. Another option is to use a tool called the Paper Tiger. This tool has multiple small pins attached to wheels. It works by making small holes as it rolls over the painted wall surface.
Use a chemical paint stripper as a last resort if you can't remove the painted surface. This is a toxic product and it can cause damage.
Strip the paper using a chemical wallpaper stripper. This is mixed with hot water and then sprayed on the wall surface. It dissolves the paste and helps lift the paper from the wall. Apply the mixture with a spray bottle or paint roller. Only wet an area large enough that you can remove it within 15 minutes to avoid damage.
Rent or buy a wallpaper steamer as an alternative to the chemical wallpaper stripper. This is a hotplate with a hose that uses a hot water reservoir to heat the water and direct steam to the hotplate. Have a baking pan nearby to put the hotplate in when you're not using it.
Start at the top of a wall. Hold the hotplate against the surface until the wallpaper softens. Move it to another area to soften the new area while you scrape the one you just softened.
Avoid using the hotplate above chest height. Use a step stool, wear rubber gloves and wear a long-sleeved shirt to help prevent burns caused by water dripping off the hotplate.