Scientists must often describe complex ideas, and when they do their writing will be complex. But scientific writing is often more complex than it needs to be.
Clear thinking becomes clear writing; one can't exist without the other. It is impossible for a muddy thinker to write good English (Zinsser 1985).
To which I would add the corollary: "Poor writing usually comes from poor thinking."
You are likely to be thinking and writing clearly when
the subjects of the sentence name the cast of characters, and
the verbs that go with those subjects name the crucial actions those characters are part of.
Readers are likely to follow your reasoning when
the subject of your sentences are ideas that you have already mentioned,
the subjects of related sentences are related to one another, and
the topic of each paragraph is introduced at the end of the first sentence.
Every paragraph should make a single point, and readers should find it either at the beginning or the end of the paragraph. If a paragraph introduces either a section or the whole paper, the point should come at the end (Williams 1990).
Short paragraphs are easier to understand than long ones. You may have to write a long paragraph when there are many parts to the point you are making, but your readers are likely to thank you if you break that one point into several.