Lawyers HELP?

I just want to know....how do lawyers go about charging people? I know that their are contingent fee, hourly fee, and retainer fee, but i'm really talking about per hour. Let's say that I'm a client and your my lawyer and you tell me that you worked on my case for 5 hours today and you charge $250/hr. how do i know that you REALLY worked on my case for 5 hours or just not lying to me to get my money?