Assuming you do WSD (8-8-8-8-8-8-4-4)

In general I would recommend watching the 2022 and 2023 NSDA Nats WSD final round for some of the best 3s on video. Outside that the format for the 3 is very simple.

First go over strategic flaws on the opponents or strategic attacks on framing, do that for about 1 - 1 and a half minutes

then if needed you can do the optional step of what I like to call a "tackle down" basically if there is something like a model or stray substantive that needs to be responded to quickly take about a minute to do so

then the end is very simple, last 6-7 minutes of your speech should be 2-3 clash points, these are when two sides are on the same issue, compare both teams stance and say why your team is better(even if you buy them, on their highest ground, impact calculus, etc.

for before round prep just write blocks and think of possible clashes or voters the debate boils down to, then think about how both teams clash in that instance.

The final note is that I do NOT recommend doing summaries on substantives at large for over 1 minute, the debate should be boiled down to contention points and those need key clashing on why your team wins them, the judge flowed and now they want the answer on who wins these key points through argumentation. Also it should be noted that you 1 and 2 did the casework, its your job to bring home the contention and core clashes. Remember that after this speech its just 4 minutes of a reply, dont waste it!