One habit of mine is to use the same character over and over.

I keep the name, appearance, personality, and typically the same skillset, and then completely adapt her for the new Rp I'm in. 

She's actually a fairly fluid character, I'm always changing and altering her to fit whatever new direction I want to take things in, or how the RP world looks. I wouldn't use the same version in a gritty crime RP as I would a high-fantasy Rp. They're different universes, and require some differences to make them make sense.