The first step of wallpaper removal: NEVER put it up to begin with.
Please. If you are thinking of moving out of your house in the next century some time, don't hang wallpaper. You might think that there is no way people won't love your paper, but trust me it is a guarantee that someone will hate it. Remember how stylish the dark background wallpaper with teeny tiny flowers was a decade or so ago, or the large striped paper with a 12" border around the ceiling that made the room look like a big hatbox, or the cows and ducks in pastels phase, which screams outdated like your parents avocado green appliances. Yeah, how many of the people who hung those wallpapers now regret it. Or to be more accurate, how many current owners of those houses regret it.
You don't want to be that previous owner. You know that one that is talked about at dinner parties and neighborhood gatherings. The previous owner with no skills and even less taste.
One day you will sell your house. And the new owner will be faced with your wallpapering decisions. They will wonder how you could have ever thought it was worthy of hanging on the wall. Then when they are removing it and it has adhered to the wall and tears the plaster off in chunks, they will curse you.
If you can't follow this advice, if you just have your heart set on hanging wallpaper, please, for the love of all things holy, don't paper every single room. Confine yourself to one or two rooms.
Okay, so now you need to remove wallpaper. Where do you begin? Hopefully whatever wallpaper you are trying to remove has been hung properly.
There are many different ways to remove wallpaper. Some people use a steamer, a method I personally don't recommend. Unless you like to be aggravated and to burn yourself periodically.
Step One: Acquire your tools
You will need:
A scraper, I prefer to use a five-in-one tool above all over scrapers. (That link will being you to a site that sells them 5 for under $30. You can buy them and invite your friends over to help!)
A product such as DIF wall paper remover
Paper tiger, or something similar to score the wallpaper. If you are doing a small area using the pointy side of your 5-in-1 tool to CAREFULLY score the paper will work fine. But for larger areas you are much better off using a tool designed for the purpose.
A large sponge
Using your paper tiger score your wallpaper. Score it as much as possible. It makes the next steps easier.
Apply the wall paper remover using a roller and apply like you would wall paint. Allow it to sit until it has soaked under the wallpaper. Work in smallish areas because you do not want the remover to dry on the walls.
Pray that the person who installed the wallpaper used sizing so that the wallpaper comes off quickly and easily.
If you are like 95% of the homeowners removing wallpaper you will discover that the person who installed the wallpaper decided to skip the step of applying the sizing to the walls. Now is when you begin swearing. Be creative with your cuss words.
Using your 5-in-1 tool gently scrape the wallpaper off the wall. Gently being the key word. You do not want to cause any more damage to the wall below than is absolutely necessary. You might need to reapply your wallpaper removing product.
Continue around the room until all the paper has been removed. At this point you might notice that there are bits of wallpaper glue still stuck to the wall. Using your sponge and a bucket of hot water, sponge down the walls to remove the residue.
Allow the walls to dry for a few days before you do anything else. Depending on how easily the wallpaper came off, you might need to get out some joint compound and patch some ares of your walls.
Now you can decide if you want to wallpaper again or paint.
I am guessing you choose paint.