I used to skate Cons a lot and started to notice some trends here before I stopped skating them altogether:
CTAS (chuck taylor) models: 0.5 - 1.0 size down
JP Pro models: 0.5 size down
Breakpoint Pro (discontinued): TTS
Checkpoint Pro: TTS
One Star Pro models: 0.5 - 1.0 size down
One Star CC Slip Pro: 0.5 size down
Pro Leather Models (Al D, Hopps, non Cons, etc.): TTS
Fastbreak Pro: TTS
Sumner: 0.5 size down
Star Player S: 0.5 size down
A good rule of thumb is if its the Chuck Taylor sole, size down. If it's a cup, it's likely TTS, and if it's a different sole like on the Checkpoint, it could be TTS or half down.
Now, most of the shoes that you go half down on will fit you comfortably. If you want them (in my opinion) almost suffocatingly snug, then go 1.0 size down. I don't recommend it, though. A fuller insole swapped in at the 0.5 size down would fill the shoe out better/skate better/fit your foot properly. Results may vary from foot to foot, and mine is medium, not too narrow and not too wide at size 11.
Sorry if this is unwanted but Cons sizing CAN be a nightmare but doesn't have to be