New work

I've just been asked to make a couple of short movies for a company my girlfriend works for. As I new to the business I have no idea how much to charge. Should I charge by the minute of finished film or by how long it takes to do? Any help would be great.
Thank you.

um.

shouldn't you charge cost + 33% minimum?

Ok, fair point.
Ta.

There is no real cost, only mini DV tapes and a couple of blank DVD's. The main thing is time.

time is a cost. what's yours worth?