Random background
I normally run a background for a VERY long time on my computer. I only actually make a small few, and they are normally either part of a running joke or just something I was playing with.
I typically prefer to have images that are either shorter or thinner than my screen size or even one that leaves a lot of open space around the edges. Icons sitting over my desktop image really annoy me to no end, so I like some blank space to put the few desktop icons I have (normally 3-5).