Wallpaper installation is such a complicated and involved process that it's impossible to go into it step-by-step in the space we have here. Nonetheless, there are a few basics you should know, and look into, before you dive in. What follows is a quick breakdown of the major steps, in order, so you can start planning your wallpaper installation accordingly.
Make Sure You've Got Everything You Need Before Starting
Wallpaper installation requires you have a number of materials on hand in order for the process to progress along smoothly. Just to name of few of the necessary materials, you'll need spackle, sandpaper, scrapers, a seam roller, a smoothing brush, a razor knife, and of course wallpaper and adhesive. And that's just for starters.
Wallpapering isn't a small project, and it's probably wise to price out what you'll have to pay for materials right off that bat. Hiring a decorator to come in and do the job for you might actually save you money in the end. Also, remember that once you start papering, there's no turning back. So make absolutely certain you've got everything you need before you start.
Prep the Walls
One of the main reasons wallpaper installation projects go bad is improper preparation. Do not cut corners here for any reason! Make sure the wall is absolutely clean to start with, and that all holes or blemishes have been repaired and smoothed over with spackle, then sandpapered. If your wall already has wallpaper on it, you're better off removing it before you start than just putting up a new layer over the top. The moisture and weight of your new wallpaper can easily cause the previous layer to come loose during installation, meaning all the work you've done up to that point will have been for naught. And if your walls are painted, beware of glossy finishes. It's worth your time to cover them with a coat of primer paint before you paper, since glossy finishes can prohibit the new wallpaper from adhering properly.
Prepare Your Paper
Once your walls are ready for installation, great care must be taken to cut the paper to the right lengths to ensure proper coverage. Measure carefully, giving yourself at least a 2" overlap at the ceiling and floor just to be safe. When it comes to wallpaper, it's always better to have too much rather than too little. You will trim off the extra later for a straight, smooth line across the board. If you've purchased self adhering wallpaper, make sure you follow instructions and soak it long enough, and also make sure you let it cure after the soak long enough for the adhesive to get into prime form.
Professionals will often also use a paste along with self-adhering materials just to be safe, but be sure to educate yourself on this process, and check with the manufacturer of your wallpaper before you go this route, just to make sure it won't present any unforeseen problems.
Hanging Your Paper
Perhaps the most important part of any wallpaper installation is hanging that first piece. It is a make or break proposition, since any mistakes made in getting that first piece up straight are going to get more and more obvious as you work your way down the wall. Use a level to make sure that first piece is going up plumb, and don't use the corner of the wall as your guide. They can be surprisingly crooked.
Just to be safe, purchase a book on wallpaper installation before you begin, or check one out from your local library, to make sure you're doing everything you need to be. And keep in mind that there's no shame in hiring a pro to come in and do the job for you. Wallpaper can be an absolutely beautiful addition to your home. It can also be one of the most frustrating home improvement projects to try alone. Hiring a pro is often well worth the extra money spent.

Matt Goering, formerly a carpenter and house painter, is a freelance writer for the home improvement industry who has published over 600 articles.