I'll add my Just do it" to the chorus. Just think how you'd feel in 10 years time if you never even started.
Do some research into projects of this type, portraits etc so you can see what over people have done and in what style.
As you said, start off with your close family and friends, then print these up and review the images, if you don't like them then as it's family I'm sure they won't mind sitting again as you refine your style. Also, it gives you something to show to other people as you widen your net of subjects. Showing people what you've done will help them to understand what you are doing and perhaps open a few more doors.
Best of luck it sounds a great project. I'm sure you'll do it justice.