I always start with very basic premise, and build up the character and the backstory based on experiences, interactions etc. in the actual game. This is why people in my factions don't "skip" ranks in RP - start from the bottom, build your way up while building up the character's story through experiences and interactions.
Think movies where the protagonist is often coming in from the academy, after being recruited to the pirate world, or one that has lost his memory, so the audience gets to explore and develop with them, as opposed to just being a pre-set set in stone NPC without development and unearned attributes.
Even e.g. on Caps I'd have the big boss be a faceless CO, while "my" character is a lower level officer not making big decisions - and then you build them up through experiences, get attached to their story that progresses organically
