How Do You Price Jobs?

I was wondering how you guys price jobs? When my dad price's job's he usually charges by two different ways depending what type of job it is. The ways are (1) how long he will take to complete the job OR (2) minimum charge of $300.00.
I would like to know for a few different reasons, that I will mention. The reasons being (1) I don't want to get into the mess that my dad gets himself into, (2) I would like to know what I should be pricing jobs at according to other contractors, (3) I'm going to College to become a General Contractor and I don't know if they are going to teach us how to price jobs and if they are I want to have an idea so I can be like first in my class (I messed up big time in high school and this is my last chance to make it), (4) My dad is giving me a painting job to do, its a fence and it basically going to be my contract so I get all the money, I don't know how big it is but he told me to charge whatever I think is reasonable. I don't want to overcharge and have problems getting my money but at the same time I don't want to undercharge.
I know that some tile layers will charge whatever the tile costs per square foot to install (ex if the tile cost 5 per square foot then they will charge 5 per square foot to lay). I know for people who install doors price the installation similar to the tile layers, they price the job just a bit more then double what the door costs just in case they damage it and have to replace it. I know that fence builders charge a minimum charge of "x" amount of dollars (which my dad's minimum charge would be $300 a day) when is less then "x" amount of feet and then anything of that "x" amount of feet would be somewhere between 18-30 dollars a linear foot.

Originally Posted by Driftwood That's WAY low, Dad's in trouble!

Originally Posted by tinner666 I've never been good at pricing remodeling and often lose money.