From Real Simple Article
HOW CAN I TEST OUT WALLPAPER
Wallpaper samples are small (about 8-10 inches), so they don't give you a sense of what a finished room will look like. Most vendors offer helpful wall size views of their wall paper designs online. But nothing compares with the real thing, so if you're almost certain about a wallpaper pick, you might want to invest in just one roll and try it out: Using blue painters tape on the back, hang from the very top of the wall to the floor. If you can place the paper opposite a mirror, you'll have two views, which will offer an even better feel for the final effect.
CAN I HANG WALLPAPER MYSELF
Wallpaper is pricey, and hanging requires skill. Unless you know what your doing, its best to hire a pro. Find one in your area or even better through a referral.
WHATS IT ALL GOING TO COST
Installation prices vary depending on where you live and the specifications of the space, but for a 10 by 10 foot room with eight foot ceilings, expect to pay between $500 - $1200 for labour (and expect the job to take one to two days). Most wallpaper is priced and sold in double rolls that are about 9 - 11 yards long. Your installer will tell you how many to purchase. For the room size above, you would need six to eight double rolls . Depending on the match and how the particular pattern lines up strip to strip you may need more paper than you think. Your installer will take his best guess and might err on the side of more. This is because its nearly impossible to know exactly how many rolls are needed until installation is in progress, and could take weeks or months for an extra roll to arrive. Also paper ordered from a new dye lot wont necessarily match the rolls you have.
ANY MONEY SAVING TIPS
If you have more than one room to paper, you can save a bit by doing those rooms at the same time, (rather than say, one now and one in six months). A chunk of the labour cost is related to setting up, so twice the space probably wont mean twice the price.
CAN I DO JUST ONE WALL
This is a great way to enjoy the thrill of wallpaper without spending a lot. For the most impact, choose a wall with no windows and no doors, and paint the rest of the room the same colour as the background of the paper. This makes the space feel cohesive and keeps the feature wall from seeming out of place.
Your installer will probably use an oil based primer to prep the walls. If you have chosen an especially delicate paper, he may apply liner paper, which absorbs excess moisture and helps everything dry faster. Trimming the paper involves slicing off the selvages (the edges that have no pattern on them) with a single-edge razor. Some papers come pre-trimmed. Based on the paper, your installer will decide what type of adhesive to use. The two most common are a clay paste and a cellulose paste called "clear hang". To eliminate bubbles as the paper goes up, the installer will use a plastic smoother, or a paintbrush. For the paper to sure properly, the room will need to be about 65 degrees Fahrenheit, extreme temperatures can have an adverse effect on drying. After 24 hours you're free to rehang pictures and fully enjoy the space.
GOOD TO KNOW
Metallic wallpaper can scratch just like metal. Watch out if you have pets or kids. The same holds true for papers with a super-matte finish: Too much hands-on contact can mark them up. Flocked papers can get dusty. Use the soft brush attachment on the vacuum.
Grass cloth adds depth and texture without any pattern. Decorators love it for bedrooms.
Steam and water are hard on wallpaper. In a kitchen, don't hang wallpaper near the sink or the stove. A bathroom that has a shower or tub will age paper faster than a dry room will. You might want to paper a powder room instead.
Crooked old houses with walls that are less than straight look best with busy patterns, which hide imperfect corners. Linear designs (like stripes only emphasize the trouble).