The double the hourly rate thing works sometimes and other times doesn't. My software engineer buddy only charges for about half his time while I've known others who worked all the time and charged all the time.
Thanks all, I booked my first gig. We just discussed the project and he’ll pay $125/h for first phase for the first 50 hours. After that, my rate will drop to $50/h. (my estimation is 40 hours for initial phase. We will discuss the second phase after first phase is complete. Dude was very understanding that I haven’t worked as a consultant before. His main worry was the project dragging on, hence the significant price drop after 50h. Seemed reasonable to me.