How is it done? You must study good models, practice steadily, and learn to develop and support suitable arguments.
The whole point of schooling—of the weary grind in learning certain things by rote (whether a foreign language, English grammar, or the multiplication tables of old)—isn’t to acquire facts but instead to train your mind to observe keenly and reason soundly. Even bread-and-butter studies are profitable primarily as a means to this end: mental discipline.
Writing clearly is no exception. A clear style proceeds only from a clear mind. A hazy mind will never create a clearly written page. So one good exercise in exact thinking and clear expression is to try describing your own home or neighborhood. Can you precisely translate your mental images into vivid and interesting depictions? Have you cultivated this knack?
If you have, then you’re well on your way. Then, as a legal writer, you must devote yourself to studying the kinds of legal arguments that courts in your jurisdiction are most likely to accept. You’ll want to know how to frame both textual arguments and pragmatic arguments, and how to marshal caselaw that supports you and debunk the applicability of caselaw that doesn’t—all the while letting it play only a supporting role. On the one hand, you need copiously supported, well-organized points; on the other, you must exclude distractions and byways.
Judicial attention is a scarce resource, and it mustn’t be squandered.
When it comes to effective writing, there’s a lot going on—both large points and small. If you recognize this truth, you’re predisposed to acquire the necessary techniques.
Further reading:
Garner, The Winning Brief 3–7, 660–73 (3d ed. 2014).
Garner et al., The Law of Judicial Precedent 80–104 (2016).
Scalia & Garner, Making Your Case: The Art of Persuading Judges 22–23 (2008).
Scalia & Garner, Reading Law: The Interpretation of Legal Texts 31–41 (2012).