You could start by reading a copy of "The Elements of Style" by William Strunk, Jr. with revisions by E.B. White, MacMillan 1959. It's a small book and very readable.
After "The Elements of Style" you could read a book of Hemingway short stories and try to copy his crisp, clear style.
An assignment I had many years ago in an expository writing class was to write an essay of five paragraphs each beginning with a topic sentence. Then we were asked tp combine the five topic sentences into a single paragraph which distilled the content of the essay. One of several Hemingway stories we were assigned to read as an example of good, clear descriptive writing was "A Clean Well Lighted Place."
Then write, write, write and revise, revise, revise.
Here are a few suggestions from Strunk and White:
"Planning must be a deliberate prelude to writing."
"Ordinarily a subject requires subdivision into topics, each of which should be made the subject of a paragraph."
"As a rule, begin each paragraph either with a sentence that suggests the topic or with a sentence that helps the transition."
"...breaking long paragraphs in two, even if it is not necessary to do so for sense, meaning, or logical development, is often a visual help."
"Use definite, specific, concrete language."
"A period of unfavorable weather set in." Better: "It rained every day for a week."
"He showed satisfaction as he took possession of his well-earned reward." Better: "He grinned as he pocketed the coin."
"OMIT NEEDLESS WORDS.
"Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts."