Good advice from both Henry and tomh. Hot water and vinegar has always worked well for me, however, I use a garden sprayer to "wet" the wallpaper. You can cover alot more territory quickly and don't have to deal with hot water running down your arms like when using a sponge. Like Henry says "let the water do the work". It takes a while for the water to soak through the paper and loosen the glue. I usually wet the paper twice (waiting about 15 mins in between) and then give it an additional 10 mins before I even try to remove the paper.