As with so many home projects, a proper foundation is important both for aesthetics and longevity. Wallpaper is no different. Wallpaper adhesive requires a proper surface to perform its job. With proper preparation, wallpaper will remain on the wall until it is time to redecorate, and then, removal will be relatively easy.
It has been said that many people have fallen out of love with wallpaper because it has not stuck properly and /or has been exceptionally difficult to remove. With these failures in mind, people have been willing to settle for monochromatic paint or the faux finish fad. A proper foundation will prevent the need to settle for these other decorating options.
In the '70's and '80's I hung exclusively on oil based paints. I would apply a top quality alkyd resin coating to the walls and install the wallpaper. The paper stayed where it was hung, and removal was gratifyingly easy. But the rules have changed with the new VOC laws that have caused a dramatic reformulation of solvent based coatings. Now the only new coatings I can universally recommend are those whose resins are 100% acrylic. There are a few other specialty waterborne sealers that perform excellently under wallpaper, but those would be recommended on a case by case basis. Why the necessity of using a top quality 100% acrylic primer sealer? Low-end or bargain priced paints from discount and big box stores are simply inferior. They can not withstand the moisture involved with wallpaper. Many varieties of wallpaper can take 48 hours to dry and some even longer. Cheap inferior paint will become saturated, "rewet", and lose its bond with the wall. High quality coatings perform as they should. They resist the moisture and retain their bond.
Another issue is dust. Newly constructed or newly repaired walls must be 100% dust free to assure proper adhesion of the primer/sealer. A vacuum and brush will not remove all the dust. To check for dust, run a bare hand across the wall. No dust should show on the hand. Wiping the wall with a slightly damp cloth will pick up all the dust. Many find that a damp micro fiber towel works perfectly.
Application of a specifically formulated wallpaper prep-coat will be final link in the chain that will properly hold the wallpaper to the wall. Wallpaper prep-coat is technically NOT sizing. For that differentiation, you may want to read my short piece, Wall Size, what's it all about. Wallpaper prep-coats do not have the sealing properties for priming raw sheet rock, joint compounds, or plaster patches. Those porous materials need a 100% acrylic primer/sealer under the wallpaper prep-coat. And those primer/sealers should be allowed to dry for at least 48 hours before wall paper is installed.
When proper techniques and high quality materials are used to build a proper foundation, all that is needed is a professional paperhanger who knows how to properly install the wallcovering.