i'd like to brighten up my room. the walls are dingy and one wall is covered in 70's wallpaper. :o which is faster, cheaper, and easier: wallpaper or paint??? any advice much appreciated.

I am interested in wallpapering an entire room in my new house and I would like to know what is the best way to do it. (It's my first time) I found some nice vinyl style wallpaper at Home depot and wanted to do it myself. How do the walls need to be prepared so that the wallpaper will stick properly??? What glue do I use to stick the wallpaper??? What is the best way to cut and merge pieces??? how long will this take to do?? I would say the room is 12X12 with and about 11 feet tall. Any other pointers, or tips would be very much appreciated. Also please tell me what materials I need to buy. Thanks again :D :D :D