I used to have a long list of advice here for people taking the brave leap to write their first novel, but it comes down to this:
No one is you. And that is your power.
Of course, there are correct grammar and ‘good writing’ rules that all authors should learn if they want to write a professional book. But authors are also artists. Once you’ve learnt it, don’t be afraid to rip up the rule book, or rewrite it.
Have fun with your writing. Push ‘traditional’ boundaries. Be creative. Find your unique voice and style. Don’t let anyone tell you what you should write or how you should write it.
There’s a well-known saying that no two people ever read the same book. Well, no two people ever write the same book, either (unless they’re plagiarizers =P).
Even if you follow a ‘typical’ story arc like ‘boy-meets-girl,’ you won’t tell that story in the same way another author would. And that’s the beauty of it all.
Find your voice. Develop it. Nurture it. And always, always, stay true to it.