How to quote a price for family portraits?

I'm a amateur photographer and i'm doing my first family portrait shoot. the family asked me to come up with a price quote and i have no clue of what to charge since i've never done this before. It's gonna be a family of six, all adults, outside. i'm shooting with a nixon D 40, Like i said i'm just starting out so i need any advice i can get, if you have any posing ideas i could use help with those too