Buy a Paper Tiger and an enzyme solution for breaking down the glue.
When using the tiger, only press hard enough to break through the surface of the paper. If you press too hard, you'll end up perferating the drywall/plaster too. Keep it cleaned out as you go too. DIF is a cheap and very effective product for this job. There are home made solutions but I've never tried them. Follow the DIF directions to the T. Make sure the water is hot and make sure you don't start peeling too soon. It does take time for the enzyme to work. Lay plastic and newspaper along the base of the wall to catch excess water. Buy a BIG sponge like they use to wash cars. I used a garden sprayer when I did 4 bedrooms, a hallway, a foyer, and a stairwell. It was better on my back and I wasted less water. Keep a BIG pot of water always boiling on the stove. When I wasn't using the sprayer, I set it in a bucket of hot water so it wouldn't cool down. Cool/cold DIF doesn't work.
If you have vinyl wallpaper (as opposed to paper wallpaper), you may not find this process working too well. If this is the case, my suggestion is to carefully peel off whatever wallpaper you can, then use the tiger, then use the DIF solution. The key is to get the DIF behind the wallpaper so it can do the job. Usually, it take 2 coatings of the solution because the 1st one mostly soaks the wallpaper (and does some of the breaking down of the glue) but the 2nd one really does the job. Once you get going, you'll develop a rhythem. Once you get to that point, you can start getting ahead of yourself. For example, when you apply the 2nd coat of DIF to a wall, you can apply a 1st coat to the next wall. And so on. This way, you're always a bit ahead of yourself and you keep working. But the key is to let the solution do its job. If it's not working, you may be trying too soon! SO be patient and read those directions. If you have a wallpaper store in your area, they may have brochures on how to do this jo.
I thought I was going to be short and sweet. Oh well, my best to ya and hope this helps.