Selecting the right wallpaper is easier than actually hanging it. But the job shouldn't cause undue anxiety if you understand the basic techniques. Wall preparation and layout are critical to a good-looking job and are just as important as the installation or hanging process.
The first step in hanging wallpaper should be sizing the walls. This makes it easier to slide the paper around without tearing while you align the pattern. Because it seals the wall, sizing makes paper easier to remove later.
Premixed sizing is easier to use but more expensive than the type you mix. Either is simple to apply. Use a paint roller and pan to spread the somewhat watery solution. When it's dry, the wall is ready for papering.
When hanging wallpaper with a light-colored background on a dark wall, you may be able to see minute misalignment between seams. Prime dark walls with a coat of inexpensive white latex primer or use a combination primer-sizing.
Begin layout by establishing vertical guidelines to help position the paper. Even with guidelines there's sure to be some misalignment between the first and last strip of paper you hang. To conceal this, lay out your job so you start and finish in an inconspicuous spot, such as over a door or a window or on the least conspicuous wall.
Hold up a roll of paper where you want to begin. Make a pencil mark equal to the paper's width minus half an inch. Use a carpenter's level or chalkline to make a vertical plumb line through this mark.
Align the edge of your first strip to be parallel and about half an inch inside the layout line. This prevents the line from showing through the seam but keeps the paper's edge close enough for accurate alignment.
Don't cut the first strip by measuring it. Take the roll over to the wall and unroll enough paper to reach from the floor to the ceiling. Hold the paper in place at the ceiling and move it up and down, so you have a complete pattern at the top (if your paper's pattern requires alignment).
Make a light pencil mark on the paper at the ceiling. Then measure down from the ceiling and mark the distance that the wall is high. Add 2 inches to this measurement for trim at the bottom. Make a small cut with a pair of scissors, fold across the paper at the cut, then use the fold as a guideline to cut the strip. Test fit this strip.
To cut the second strip, unroll the paper and lay it next to the first strip. Move up the paper until the pattern matches (the wasted paper should always be at the top of the roll). Cut the paper so it's 2 inches longer at the bottom, leaving some paper to trim at both ceiling and baseboard.
Avoid cutting a large batch of strips until you've tested a few pieces of paper to see how the pattern is lining up.