Edgar Rice Burroughs says

If you write one story, it may be bad; if you write a hundred you have the odds in your favor. Play the long shots. It's better, of course, to write one good script than a hundred poor ones, but usually you must write a hundred poor ones before you can do one good one. 

When you write a story, remember that you are undertaking to entertain several million people. You wouldn't go before an audience of fifty with a poorly prepared speech. Why 'dash off' your message to millions?

Get the habit of work, and quit being an 'inspirational' author -- which is merely another name for a loafer. Don't wait for ideas to come. Go after them. Don't write every now and then. Write every day, if only for a little while. Be a worker, not a poseur. The only real 'literary people' are those who work at it. Those who make good are the ones who keep so busy that they have no time to show off. Those who pose are not literary. The poseurs want to sit down now and then and dash off something for which they will receive a large check that they may show their friends and brag about. The real literary chap doesn't call himself a 'literary man' any more than a real newspaper man ever describes himself as a 'journalist.'

When a professional diver enters the water there is no splash -- just a clean-cut cleaving of the water. That's the way you should slip into your story; no fussing, no fooling around, no labored explanation. 

The first thing in the morning, I go over what I've written the day before, correcting it. I'd advise the beginner not to waste too much time changing a word here and there but to see what he can do to make the plot better. Polish that rather than merely the form.

Don't drive your story to a predetermined finish, just because that's the way it came to you. Let your plot go where it will. If it goes in the wrong direction, you can always pull it back. On the other hand, you may stumble on a far better climax than the one you first thought of. Don't get the idea that you're through with a basic plot when you've written one story from it. Keep it and sprout another -- or three or four. It's easy!

A rocket looks pretty going up, but no one watches the stick come down. Let your climax and finish be simultaneous. If Harry breaks an arm rescuing the heiress, don't tell how his arm became healed. He's got the girl, and that's all we care about.