I've said before that clarity and simplicity in copywriting are important.

Just to pound the point home.

AFTER I've finished writing something, I go back through it and look for ways to make it shorter without losing the idea.

Take out words that don't contribute.

Use shorter, Anglo-Saxon words in preference to Latin and Greek. "Walk" don't "perambulate."

Rephrase to shorten.

Break sentences up into shorter sentences. Make paragraphs short.

If you have a lot to say, you can say it at length. You can repeat yourself to drive a point home. But the fewer and shorter words to deliver the same idea, the punchier it will be - and the more people will get the message.