Personally I usually go out the first day on a trip as a feeler. I go with nothing. Literally a couple bucks, MAYBE a debit/credit card (I've got multiple credit so if one does get pinches, life isn't over) and a photocopy of my passport. That's it.
I don't scout sites specifically, but I just wanna get a general feeling for the city. You can usually kinda decide if you're gonna be safe, or not. Obviously this isn't scientific, stuff can happen anywhere/anytime, but after walking the so called dangerous neighborhood in San Jose, CR at night I deemed it safe enough. So while the next night I didn't go cavalier, I did relax a bit.
I also generally like to stand away from crowds, not as a precaution per se but because I don't like to be mixed in like that. In Medellin I'm almost always the last one on the metro. Now, at rush hour it's harder, but I'd rather miss a train, than have this happen. Plus, from there, you can scope out people too. Not that you wanna brand anyone with that pickpocket brush, but if you had seen this water bottle get dropped at someone else's feet, MAYBEEEEE you'd have an itch and be like "what's up with that".
Glad you only lost a bit of cash though. As always never travel with a passport unless you have to. IE from the airport to hotel. My other trick, and as dumb as this may sound, I've usually got my hands in my pockets. If I can, both, if I need to hang on to a rail or something, I usually try and keep the one with valuables. MAYBE that makes me more obvious but then at the very least they'll have to get my hand out of there before they can pinch anything and that's IF anything is in there.
One other thing I often do, I don't stop moving much. Maybe it's just an OCD thing I have but when waiting for a train I'll usually tour the platform, walk back and forth, pace, whatever...again away from the crowd. So perhaps there's less likely a chance of being marked?