Registering Your Professional Name?

Hello,

How do you register a professional name that is not your real name for use in the entertainment industry?  Do you register it as a trade mark or do you go for a change of name declaration? 

I'm concerned about legal difficulties that may arise.  For example, if the name on your passport is Timothy Idibia and the name in the credits is "2Face Idibia", how do you prove that you are "2Face Idibia"?

And how do you pretend others from using the name or posing as you?

Thanks.