Have a simple logo.
It need not be what your company does. Does McDonald's logo show a hamburger? Nooooooooo. The apple logo has a logo for an apple. Does it look related to computers?
Think about the size. It should fit in many things. Ranging from large banners to tiny business cards.
Have a the correct ratio. Not too long too and skinny. Not too short and fat.
THe logo should make an impact on the viewer