I'm a little more generic in fleshing out a PC. I use a minimal system based on who the character was, what he is now, and what will he become. I can start with any of those ideas first and build off them for the other for
I wanted to play a Paladin that was more street smart than the average pally. That is my "who he is now". To explain where he comes. from I have him as a real evil guy who committed atrocities. He was killed and the Gods resurrected him and he became a Paladin in service to the Gods. The Players has a notorious background, but he is now a servant of Good. He uses his past background as a cover to get what he needs to fight the forces of evil. That is the Now.
Evidentially, the forces of evil will figure this out and it will be less useful. But he still is wanted for the crimes committed before his transformation and he will have to decide if the fight against evil is more important than Justice denied. That is the Future... which could change as he has relations with other PC's and encountered many NPC's along the way.