I know that if I were ever to attempt to wallpaper a room, a disastrous Lucy & Ethel Paperhangers situation would undoubtedly occur. For the more dexterous of you, wheatpaste is a super-cheap, all-natural (even organic!) alternative to conventional wallpaper adhesives.
The talented Jutta of Kootut Murut has posted a nice little wallpaper wheatpaste tutorial, conveniently in English & Finnish! She and her husband have been using wheatpaste in their lovely old home for years, and make it sound so charmingly old-timey yet easy & efficient.
And, because I couldn't resist: the cutest example of wheatpaste art I've ever seen, singing cacti on the side wall of the candyshop where I worked for years.