The logo has to have a corporate look, an appeal that if you take away the text it still is recognizable (ex:AT&T, with or without circle).
Typeset is import and color schemes are important.
Good colors orange/blue, red/gold, purple/gold
An effective logo is (in no particular order):
Simple
Memorable
Timeless
Versatile
Appropriate
In the attachment are some designs I may want to duplicate but personalize it more towards my goal of a complete logo.