I don't really think too much about character personalities. Just go with whatever I feel like.
Recently, playing angry !@#$%^&s have been rather intriguing and fun for me so I go with that. Once I get that out of my system, I may try something else.
Or I usually just let characters develop their own personalities. Usually making them interact with others tend to shape their personalities better. Or asking what others think of your character after few interactions.
