Appropriate writings gives the reader a clear idea of needs and desires. It has the right tone. He or she is neither talked down to nor buried in verbosity nor pompousness. Remember that your prime purpose is to explain something, not to prove that you are smarter than your readers. Your aim is to be read, understood, and remembered.
Good writing is readable.
It dose not require the rereading of every other sentences. It has clear transitions from paragraph to paragraph. Perhaps, clarity and accuracy are the foremost requirements for scientific writing. Simple language is often the key to clarity. Writing is difficult, but the best way to start is to start.