Try a friend or family member first, someone you can trust to give an actual opinion not just tell you what they think you want to hear. Someone who reads a lot of books, especially in the genre you are writing, can be very helpful! Or, you could try joining a writing group and ask for readers who would be willing to help. Or, you can pose excerpts here and see what readers say.
I will warn you, though-hubbers aren't likely to give you decent constructive criticism in their comments, though. You'd be more apt to receive a lot of generic 'good job' kind of stuff. Not that that isn't nice to hear sometimes, but it isn't really helpful when in the editing process. A friend who will be honest with you is your best bet, I think (I'm actually writing a hub about that now.)
You could try reaching out to fellow hubbers in the forums and see if someone would be willing to read some, too.
My questions to you would be, 1)what type of novel are you writing? and 2) what kind of feedback are you looking for?