Yesterday, I stole one idea form Bulldogs! and today I'm going to steal another.
Back in the day, Feng Shui presented a very interesting way to handle skills that worked very well for it's wide, loose model. In short, a skill represented three things. The first, Physical Ability, was the traditional meaning of a skill - actually doing the thing the skills described. If the skill was guns, it means shooting people. If it was Thief, it meant breaking picking locks and such. All standard enough.
The second thing, Knowledge, measured how knowledgeable you were about the skill in question. Thus, if you had a high guns skill, it also meant you had an encyclopedic knowledge of guns. This worked very well for the action-movie focus of the game, since that tends to be how action heroes operate. The thief may not be "The Smart Guy", but he can rattle off the details about a specific type of bank vault with nothing more than a glance.
The last thing, Contacts, measured the character's connection to the community surrounding the skill. This meant you knew who the other big players were in your space ("He was killed with a golden bullet through the left temple, the signature of Midas Mayhem!") but also the broader network around it, including gun dealers, collectors, specialists and so on. Among other things, this meant that a thief could find a fence or a gun-bunny could get his hands on a bagfull of guns without much real hassle.
Now, I don't know if Laws took this from another game, but for me it was a total eye-opener. By establishing these Skill Components, he'd neatly solved a ton of problems from more detailed systems that emerged from a disconnect between the character as envisioned and the character as supported by the rules. That is, even if you bought up your core skill, you would usually need to also buy up the far less rewarding Knowledge and Contact skills to avoid looking like a chump (or, as was more often the case, ignore them and hope the GM did the same).
I internalized this approach in my own play, to great satisfaction. In time, I added my own spin in the form of a fourth Skill Component for Perception (So gun guy could spot a sniper or a concealed carry without being Sherlock Holmes) and happily meandered onward.
But for all that, there was a bit of a downside to this, since it did not map to all sill lists, especially if you want to go to a finer grain. As an example, Feng Shui had the Intrusion skill, which covered a wide range of thiefly pursuits, and that worked. But if you ever needed to split it up (into, say, Burglar and Stealth) then you ran into weird questions, like what exactly Stealth Contacting meant. Is there a big Stealth community out there? Do they have a very sneaky newsletter?
Bulldogs! strikes at the root of that problem by taking a similar (but more detailed) breakdown and building _up_ from it to construct skills. The basic idea is that a skill can be used to do the following things: overcome an obstacles, make an assessment, make a declaration, place a maneuver, attack, defend or block.
Now, what exactly those mean has some system-specific weight, so if you're not clear on what "make an assessment" means, then don't sweat it (or go read SOTC) but what's important is that those are, effectively, the seven mechanical things that a character can _do_ in the system, so using them as the baseline to define the skills makes for super tight engineering.
The idea is not portable in and of itself - those 7 things are fate specific - but the idea is a fascinating lens to take to another game and ask what characters can actually _do_. Curiously, you can end up coming around to a similar space as Apocalyse World's moves this way, albeit from a somewhat different direction. In both cases the bones of system are laid bare, and the construction on top of them is made apparent to the reader.
So, yeah. It's a good trick.