there is a literary device where you say important things twice, once accurately by description and then again by example, it helps folks orient and synthesize the idea
I argue that the examples--preferably more than one--should always precede the idea, principle, or definition. A fitting audience, then, will arrive at/or could smell the actual idea themselves, before it's presented.
(It's also my plea to mathematicians/academics: please, give us more examples before you hit us with your formula-heavy artillery).
That really depends on the audience. On this topic there are broadly-speaking two types of people: those who want the conclusion first and the details later ("managers", if you will), and those who want the details first and the conclusion later ("investigators", perhaps). Knowing which class your audience falls into is incredibly valuable.
I've seen this described as a pyramid. The first group wants to see the precipice first and work their way down to the foundation. The second group doesn't want to look at any stone before understanding what it's resting on.
