If it is not strippable, put your floor cloths down to keep water or other stripping solutions from messing up your floors or carpeting. Use a steamer with ordinary wallpaper to loosen it. You can rent them and they are very helpful if you are doing more than one room. Stripping agents also work well if you're only doing one room. Mix hot water with the agent, according to directions, and wet the walls to soften the paste.

Work only a small area at a time, scraping off the wet paper with a wide putty knife or a blade scraper. Use a sponge to pick up loose pieces that are extra stubborn or get left behind.

Once all of the former wallpaper has been removed, you are ready to glue size the walls.

Glue size is a glue that you mix with water until it is the consistency of thin paint. You want to apply it to the walls with a roller or brush. The reason for glue size is that it allows the paper being applied to move while you are trying to match it to the layer before it. This is especially important if you are hanging wallpaper or a covering that has a pattern. Glue size also makes it easier to remove the new paper later should you want to.

Now you are ready for the fun part.

If you are using a pre-pasted wallpaper, you'll want to purchase a long wallpaper soaking tub and soak the whole roll at one time for quite a while. Aggitate the water periodically to make sure that the entire roll is being saturated. You can pre-cut your strips and soak them that way, if you prefer, but you'll likely have a lot of waste if you do. By soaking the whole roll at one time, you can just pull out what you need for each strip, cut it off and leave the remaining roll soaking until you are ready. But you need to work quickly. You don't want to leave the roll in the water any longer than necessary once it is completely saturated.