Writing advice often reiterates the same general rules: active voice, economy of expression, favour the concrete over the abstract.
These broad suggestions come at the expense of advice on micro- and macrostructure. We're missing a trick here. In particular, I believe great non-fiction writing out-punches the good because it manages not only to articulate ideas succinctly and clearly, but to show how they overlap and interconnect.
In business, while a good product is essential, it is almost always not enough. The product has to be presented to the consumer in an intuitive and sensible way. Often a product will have more than one USP, and its success hinges on which USP you chose to emphasise.
The same might be said of ideas. An argument---or point---will be convincing only insofar as it is presented to the reader in a coherent way.
To that end, do people have any tips, book suggestions, or exercises that will help writers improve their articles' unity, coherent, flow, logical structure, etc?
When I've first drafted a sentence, I start from the top of the list, and ask these questions in turn. Asking them forces me to think about an answer; it prevents laziness. As soon as the answer to question suggests a possible change, I make that change, and start again from the top. I repeat until time constraints force me onward.
This is a great process, because if I have very little time, I end up concentrating only on meaning. If I have all the time in the world, I get to also play with the sound of the words, and the play of the tongue.
Questions about meaning, clarity, tone, novelty, and beauty can also be fruitfully applied at paragraph and treatise levels; but my greatest concern is usually for the sentence.
1. http://diiq.org/five_stone_questions.html