Comprehensive Character Background
Character background should be comprehensive. Set an age if possible, or give a close range. If there is a hole in the background, make something up that is in line with your perception of the character and how you intend to play the character. This goes for FCs as well as NFCs.

IC Justification
Everything must have IC justification. Every skill, trait, power, contact, equipment of technology must fit into the whole of the character.

Uniqueness
When you are applying for a character, uniqueness is always encouraged. Granted, there are restrictions on your uniqueness when applying for an unoriginal character; however, you can still most definitely try to give us new and unique insights into the character. For original characters, try to be original in concept, power, background, traits, personality, contacts, skills, you get the idea... Original characters of your own creation should be as original as possible.