Good question.
My first design moment I felt good about was using 9 actions rather than 12. I'm making a cyberpunk hack, and try as I might I couldn't figure out where to put the hack action. Attune made no sense to include, and putting Hack in the same attribute as all the social actions made no sense. Try as I might I always ended up with an odd number of action per attribute, which would've messed up how resistance worked, and aesthetically I hated it. Then I thought, 'Screw it, let's just collapse these actions as much as possible' and I ended up with 9 I feel really good about.
Also seeing how Scum & Villainy has 3 ratings for each actions inspired me to use the same limit, and instead of using gambits to make up for that potential, let players acquire 4th action or attribute dots by getting cyberware.
Changing what the actions were called took some doing too. I've changed a bit of vocabulary in my hack (Traumas are Glitches, cohort gangs are teams, etc.) and that was just a lot of time spent on thesaurus.com. Ditto for what to call the playbooks.
Some of the biggest changes came straight out of Blades in the Dark, in Chapter 9: Changing the Game. I was tying myself in a knot trying to figure out how to design mechanics that Poor Beginnings and Tier Tied to Lifestyle already cover. These are important components for me as they highlight the fact that the players start as poor freelancers, desperate to try to get an edge, and the only way they can make significant progress is by the accumulation of wealth, to buy into the system, to hustle.