1) Keep your head down and write. Write, write, write, write, write. Just write. The earlier you are in your writing career, the more you also need to read, read, read, read. There came a time for me during the actual steady writing of the first draft of my novel that I couldn't read other novels--not beloved old ones or hotshot new ones. I had to become fully focused--obsessed, in fact, totally absorbed--with my own work, with the world I was creating. But until that time comes, read, read!
2) Find at least one faithful and well-read reader (maybe two, but no more) to help you while you write your first draft. Don't give your novel manuscript to everyone you meet--especially an unfinished manuscript. Too many conflicting opinions can paralyze a writer. The most important thing is to finish that first draft. Then comes the heavy editing and revising. But even then, keep your readers to a minimum. Trust yourself more at that point.
3) Write for the story's sake and for the characters and for story in the largest sense of the word. There are so, so many awesome writers out there. You can't worry about them. You are not writing for them or so you can one day rub shoulders with them. Write for your characters and for the story that burns inside YOU!
4) This is for very beginning fiction writers: the only truth you must adhere to is the truth of fiction. Don't force a character who is based on your grandmother to make all the same decisions she did. Characters take on a life of their own, and you absolutely have to let them seek their own truth, which is the truth of fiction.