You've undoubtedly got a couple of tiny holes in your wall whether it's from hanging and then moving a picture or from something else. Well, here's an easy way to fix it!
All you need is a bar of soap. Once you've located your hole, simply move the bar of soap in a circular motion around the hole. This ensure that you cover every aspect of the hole. There may be a little bit of soap residue, but you should be able to just wipe it away.
Voila! You've covered the little hole. The results may vary depending on the color of your wall, but luckily paint comes in a multitude of colors!
Idea found here.