Never give your work to a friend or family member for critique. Especially if this is one of your earliest works (Hint: You're unpublished, so it is). My ex-girlfriend used to give me her stuff all the time (she actually finished a book, but I think she's been having troubles producing a second draft for several years now). She gave most of her friends the same stuff, lapping up the compliments she got in return. It feels great when somebody says nice things about your writing.
It was the same for me, until I got to "Now, an area I think needs a bit more work might be..." and then she got offended and thought it was a personal attack against her. So I didn't read the rest of the manuscript. This was in high school, and one of her teachers also critiqued her work in a similar fashion, and she was okay when he said it, even settling in to work on those aspects.
When deciding on the quality of your work, you want a stranger, and at least a semi-professional setting (semi-professional as in: what we have in Supermikhail's Writer's Guild, where you can get solid and well thought out responses). Your friends are in a complex web of politics, in which you are a member. Their reaction to your work will largely be centred around whether they want you to like them or not. Get some people you don't know all that well, or some people who are also writers or work in the publishing industry (or, if you write a play or script, some people involved in those industries). The latter group is great, because they often know enough not to try to make it their own.
That said, my suggestion for your book-writing aspirations is to just write all the time. This year's NaNoWriMo was great for me, even though I didn't finish. Try setting deadlines for yourself all the time, since deadlines force us to do things. Remember that at some point, the writing process is going to get tedious. Try to hold on to that energy, and don't just take 'extended breaks' in the middle of writing. Save your 'extended breaks' until you are done and want to wait a few weeks or months before looking over the finished work. Writing something big is like playing an RPG in that when you get distracted and do something else halfway through, you're suddenly not all that into the story anymore and you have to start over.
You'll also get urges to write something else. Take an example from George R. R. Martin and avoid doing that, because you will never finish what you started.