I'm currently running a somewhat similar character. He's a thaumaturgist who specializes in potions and enchanted items and runs a magic shop called 'The Art and Craft'. His aspects:
HC: Journeyman Artificer
Trouble: Everyone wants my help. EVERYONE.
Gadgets, gizmos, and a touch of magic
I Run a Clean Shop - He doesn't dabble in dark magic, and in fact, stands against it when he can. It also speaks to his very ordered mind.
I Prepared for Everything... Except THIS! - Great for both declaring the perfect potion and getting compelled to NOT have the one thing on hand that would save the day.
All Brains, No Brawn - Reflected strongly in his skill choices, another great two-edged sword.
Aaaaaand I'm totally blanking on my last one.
Anyway, I'm not too familiar with Constantine, but from what I know, he seems a lot tougher and darker than my character. Still, maybe this will give you some ideas.