KISS has forever been a favourite term of mine (and probably of most designers). Your logo should be simple and memorable. Think of all of the successful companies in the world; Nike, Apple, McDonald’s, Gucci...They all have simple logos. Don’t have a complicated logo with a lot of detail. People often only have a few seconds to look at your logo and you want them to remember it.
Keep your colours to a maximum of three.
Of course, there are exceptions to every rule, but generally, you want to keep your logo as simple as possible.