Take into account your clients, the competitors and your company:
Consumers or clients must feel identify with the logo. Do not create a very sophisticated logo if you think your clients are not ready for it and will not understand it. Do not create a very simple one if your clients will not appreciate it. Analyze the competition, the graphic element they use, their composition of colors, elements distribution, complexity or simplicity, and specify where you want to be positioned against your competitors. Your graphic image must even your company activity: it should not be too elegant if the world market does not need this kind of image and it should not be too simple if the world market is looking for sophistication; if so, the client will not trust the company.
http://www.101websitedesign.com/graphic_design/Logo_Designing/
http://www.soslogodesign.com/Ten-Tips-For-Logo-Design.aspx