If you have ever had a pre-teen or teenager want to hang crazy posters on their walls, you will understand this tip; if not, and you have kids, you will understand eventually.
In searching for a method to save our walls, we came across "Sticky Putty". What a wall saver, this is the best stuff ever.
When we discovered "Sticky Putty" we were able to allow our kids to decorate their own rooms. No more worries about the tape that peels off paint, or nails(tacks) creating holes everywhere. Now, your walls are saved. There are multiple varieties available and most work very well. This has saved us through multiple interests and our kids can decorate their walls with whatever posters they are currently interested in without fear of having to repaint.