When my son was living in the dorm at Ohio State he wanted to put up some posters, but was worried about damaging the paint on the walls. The rooms were inspected when you move out, so he didn't want to have to pay for marking up the walls.
I had always heard of the Command strips, but have never tried them until now. They worked perfectly for hanging the posters and there was no mark left at all on the wall when he took them down and didn't even leave a mark on the paper poster. There were 12 strips in the package, enough for 3 posters at only around $1.50
We had to use rubbing alcohol to wipe the surface, let dry and then removed the red paper strip and applied that to the poster, then removed the black strip from the other side of the command strip and pressed it firmly on the wall for 30 seconds. When we removed the posters, we had to lift the corner of the poster and pull down on the tab, stretching the adhesive about 6 inches until it released from the wall.
The command strips can be used on many types of surfaces, such as paint, plaster, wood, glass or tile. It's not recommended for paper wallpaper.