Liking this list from V.S. Naipaul for beginning writers. Except they're also excellent for writers who aren't so beginning.
Use short words. And short sentences. Remove adjectives. And like Stephen King also says, ditch adverbs. Just say stuff.
Do not write long sentences. A sentence should not have more than 10 or 12 words.
Each sentence should make a clear statement. It should add to the statement that went before. A good paragraph is a series of clear, linked statements.
Do not use big words. If your computer tells you that your average word is more than five letters long, there is something wrong. The use of small words compels you to think about what you are writing. Even difficult ideas can be broken down into small words.
Never use words whose meanings you are not sure of. If you break this rule you should look for other work.
The beginner should avoid using adjectives, except those of color, size and number. Use as few adverbs as possible.
Avoid the abstract. Always go for the concrete.
Every day, for six months at least, practice writing in this way. Small words; clear, concrete sentences. It may be awkward, but it’s training you in the use of language. It may even be getting rid of the bad language habits you picked up at the university. You may go beyond these rules after you have thoroughly understood and mastered them.