I especially like point the second, Realise that your character does not exist outside of the things you have said:
You can write as many pages of backstory as you like, mate, but they don’t factor in one bit to the game unless you show them happening. Are you a shrewd businessman? Cool. Do some business, shrewdly, in front of everyone else. Are you a hot jazz saxophonist? Play the saxophone. Are you a wild elf struggling through social interactions with civilised people? Struggle through those interactions! Don’t go off and sit in a tree, you prick!
And this ties directly into what you can actually pull off at the table. No, I’m not talking about allowing only people with exceptional social skills to play high charisma characters. The issue is more fundamental than that.
To whit, it’s rather frustrating, as a DM who’s built adventures around a character background full of derring-do and wild escapades, to discover that said character is actually played with all the caution and timidity of a mysophobic in a kindergarten classroom.
Granted, sometimes life, and the game, conspire against you. You meant to play a more colorful character, but traveling with the happy-go-lucky pixie rogue has you playing the straight man. Sometimes that’s just the best way to do things, and you have more fun playing with the other players than your original, conceived-in-a-vacuum idea would have been. No worries there; just adjust and roll with it.
Even better, however, is when you and your fellow players can actually build these interacting personalities together. This is one of the reasons many old schoolers prefer to begin with minimal background; what’s needed can be invented on the fly that way, after you’ve had a chance to see the character in action, interacting with the rest of the party and the campaign world.
And that leads me to imagine a group character generation system in which stats and skills are created via interacting tropes that are developed through the first adventure of play. That is, you begin with the bare-bones skeleton of a character (perhaps even one suffering from amnesia) and, as you create relationships for your PC with the other PCs, you flesh out skills, bonuses, and quirks accordingly. I’ll bet you could come up with dozens of templates just by browsing through tvtropes.org.