Whenever somebody asks me if they should take a free job I answer with a resounding, no. Don't do it. Just don't. It should be a hard and fast rule in your book: do not work for free! But let's go head and look at when, perhaps, just maybe, you should at least consider working for free.
It’s hard to say no when a good friend needs a headshot, or wants to know if you can help their mom photograph some stuff for her work, or even when someone needs help shooting a school project. While non-profits and not-for-profit’s do pay their employees that doesn’t mean they have a bunch of money sitting around to pay for things like photographers. Thus, at one point or another, you’ll probably be asked to do some free work for one. Or student work, future possibilities in the field or when you simply believe in it.
For a freelance photographer, knowing when you should charge and help out. Are to very close and different things. But when friends and family comes into the picture, you can't help but say no, no, you don't have to pay for that. But also when a future project, may be intact with an internship that doesn't pay...would you still consider taking it or not?