Super Sonic

Sonic: What happened?
Tails: You fell from the sky and was unconscious! Are you alright?
Sonic: I'm fine but...Who are you?
Tails: I'm your best buddy, Tails.
Sonic: I haven't seen you before in my life.
-Tails felt kind of heartbroken, hearing that from his best friend and brother, but he knew Sonic lost his memory. He could probably regain it sooner or later.-
Knuckles: You seriously don't remember, do you?
Sonic: No...Should I?
-Knuckles and Tails looked at each other and then explained how they met and about Eggman and about Sonic is always stopping him.-
Sonic: Sounds tough. And I can really run...

We've all tried to make an OC (Or I assume we have) Anywho, there are many people who just can't do it. First thing to do is NOT the appearance. I know, it's tempting as all get-out, but trust me. It's better to get the character's personality and such down first.
First, you should have a general idea of a character's past. If you get an idea like 'flying lagarto monkey' (Not advised) Then jot it down. I hate when you have a great idea, and end up losing it while thinking too hard on how the character should say stuff or whatnot. If you jot down one sentence about them, then you can refer to...