Dragon Heist's central design choice is the seasonal villain structure: Xanathar, Jarlaxle, the Cassalanters, or Manshoon, one per run. The book is well-structured through Chapter 2 — the tavern acquisition and Trollskull neighborhood content is where most groups put down real roots — then thins out in Chapter 3 and commits to a single villain in Chapter 4. If you run it as-written, you've locked out three villain paths and the bulk of the faction content from that chapter.
The Alexandrian Remix (free, in the Essential Free Guides below) restructures this so all four villains operate simultaneously. It's the most substantive change you can make to the campaign. Everything else on this page is additive — better neighborhood content for Trollskull, cleaner chase rules for Chapter 3, an actual bank heist for Chapter 4.
One decision to make before session one: start at level 2, not level 1. The campaign's early sessions are heavily social and investigation-focused. Level 1 fragility creates prep friction without adding meaningful tension.