David A. Wimsett's Perspectives

The first draft of a novel is the initial creation of the story. The result will produce a manuscript, not a publishable book. The manuscript must be rewritten several times to craft a book. There will be many false starts, weak writing and mistakes. That doesn’t matter. I never write outlines; I just begin with a situation, put characters in it under pleasure and see what happens. Not everyone works this way. If you do write outlines before starting a book, don’t feel you must constrain yourself to them. You don’t fully know the story you’re writing or the characters you’re creating until you work with the prose for a while.

As you write, concepts will come to mind that you hadn’t thought of. You will realize the true nature of relationship between characters and imagine new twists in the plot. Put these things down and let your imagination run free. If you start on a divergent path, follow it to see where it leads. You may eliminate it later, but explore it anyway. It might lead to something better than you originally envisioned. The final book may bear little resemblance to what you considered in the beginning.

Never go back and edit anything in the first draft as you write. If you realize something needs to change at the beginning, make a note on the side and continue as if that change had been made, then fix the beginning in subsequent drafts.
Now there's only one true rule in writing - you can do anything you can get away with, however the trick is in knowing what that is, and that requires a knowledge of writing guidelines. It also takes experience.

Practice good writing from the beginning. Watch grammar, avoid clichés and be selective with adverbs as you create the first draft. Don't fall back on sloppy writing. Build a story, don't just dump words. Train yourself to be a better writer with each sentence. This will allow you to grow as an author because writing is a life long learning experience. It also makes life easier with the second, third, fourth and subsequent drafts to craft a manuscript into a book, short story or article.