I'm writing a novel at the moment too. But i didn't have the same problem as you. I already had an idea in my head of what i was going to write before i started, then i just kept getting more ideas and before i knew it i'd already written 17 chapters. ^^
Just be creative and different. You don't have to start the book with the beginning of a story, you could write the most exciting part of it in the beginning then tell the story about that (if that makes sense, sorry i'm bad at decribing stuff like this).
And just keep the reader entertained and into the plot.
Have fun, i hope all goes well for you.
***EDIT***
Oh, i forgot to say.
Don't feel like you need to write it all in one go.
If you get stuck for ideas, just take a break for a few days until you get an inspiration again, then carry on.
That's what i'm doing and it's going pretty well, so far.