Okay here's what you do.
I don't know if this wors the same way in other countries but here in Copenhagen the trains are stopped/station closed for something like ½ an hour if someone forgets their backpack in em after 9/11, cause they have to check whether or not it's a bomb.
Time is money as we all know, and waiting is annoying. So if you can "forget" enough backpacks durring rush hours you can really delay a lot of people. All those people will be alte for work, they won't be able to work as much, so you're hitting the entire citys productivity, which in turn hits its economy.
People hate waiting, they hate waiting for the train and be late for work, and if they're not ontheir wau to work themselves, they'll hate the wait caused by all the other peopel beeing late for work "wtf it's my day off, and the bagel shop isn't open on time aaargh!"
gratz, you made half teh city pissed as well, this should increase violence.
The increased "potential bombs" that most people will hear about (cause no-one is gonna not want to vent their anger over waiting half an hour for the train) will either cause people who hear it to be more afraid of a real terror attack, OR make them loose whatever little respect they haev for the politicians for enforcing stupid laws that makes them late, instead of just ignoring a damn backpack with a lunchbox full of food.
Now you have increased fear, and rage.
All this can be achieved by legal means, cause hey, it's not like you even called in a fake bomb thread or anything, even if they find you, you did nothing but forget your backpack with lunch in it.
If you wanna top it out with soemthing illegal, start using metal-chain bolas on the electric wires in the air. if you can hit so two connects, theres a chance you'll take out the power in some area. have your henchmen do it regularily and people will egt even more pissed.
As the whole city gets more and more tense, start putting up missing posters of random people from the internet up all over town, it'll maek people think theres kidnappers or something.
More fear.
Have you ever seen the movie "falling down" if so, imagine a city full of people pissed off like that guy. Yeah, it's every villians wet dream.
Best part is, none of this should be anywhere near enough to get you jail time.
Call me evil, call me a genious, soon you'll cal me master and savior as i lure you in to my cult with promises of a better world and salvation from the anarchy and chaos.