I would say that clarity should be the king in the sense that if you want the paper to be read beyond the introduction and built upon, the best thing you can do is to present the main idea (or ideas) in the simplest nontrivial setting where you can spell everything out with all due details without making it a technical nightmare.
The standard trap people fall into is trying to present the strongest and the most general result they can prove. Nine times out of ten it turns out that the direction of the generalization they chose is not the one the other people get interested in later and one has to spend hours or weeks undoing all the sophisticated build-up and reducing the proof to its core from where everything else has to be rebuilt in a completely different way. So clearly presenting this core from the beginning would be very beneficial, IMHO. The word "clearly" means "with all relevant details and with minimal number of outside references"+"in as easy to comprehend way as possible".
By tradition, a mathematical paper has to contain some new result (preferably a solution of some reasonably old unsolved problem) just to prove that the techniques you promote are worth something but, for majority of articles, the results themselves are of much less interest than the new twists in the proofs. Your "central theorem" will, probably, be either forgotten or greatly improved in a few years but some little lemma may easily get an independent life and the simpler that lemma is, the more chances it gets (provided, of course, that it is above a certain threshold in terms of novelty and ingenuity).
The main "organizational trick" is to try to write about one thing a time. There are cases when you can and should set up "explosive fireworks of ideas" but they are rare, few people are capable of that and even fewer know how to do it in a way that illuminates things rather than blinds and confuses the reader. So, the (in)famous KISS principle is a good rule of thumb on most occasions. That one and the classical "divide and conquer" approach can work miracles as far as the clarity of communication is concerned. I heard once that a bad lecturer is always thinking of whether he forgot to include something into the course and a good one is worried if he put in something unnecessary. The same applies to mathematical writing if you want your papers to be read rather than just quoted in long reference lists under the category "and Vasya also was there and did something that nobody has ever really looked at but it would be impolite not to mention him".
Proofs should be complete and fully spelled out. It is often said that two omitted trivialities in a row can create an impenetrable barrier to the reader. Prove a weaker or a less general result than you can, if you feel that the argument becomes too entangled otherwise, but prove it in full and spend some time thinking of how to present it in the most logical and easiest to understand way. One hour spared by the writer often results in a few days wasted by the reader (which should also be multiplied by the number of readers).