Let's not get into what *I* would do, Ok?
*lol*
Truth of the matter is, nobody's going to be on your side if you pursue this. The media will laugh at you and call you lame (Search the whole phrases, "ABC News", "Shadow Hare" and "Cincinnati", this was in the news recently). The police will think you're the criminal for interfering with their work and endangering yourself. Lawyers will tell you vigilantism is a felony in most U.S. states and Canadian provinces. Doctors will want to committ you to the psych ward for trying.
Having said all that:
--Invest in parkour. Seriously. You're going to need to know how to run like hell when the bad guys get serious and *shoot at you*. Or sic pit bulls on you. Criminals are a superstitious and *especially* cowardly lot these days--they don't fight, they shoot.
--Invest in Kevlar, at minimum, and back it up where needed with heavy leathers (of the sort diehard motorcycle riders use if not thicker). You'll need it against small-caliber bullets and knives and dogs.
--Stick to the aikido--it looks good on your "resume" as a pacifist if nothing else and will eventually be useful. And in the meantime, cross-train in a kick-boxing style that will teach you the things about striking and range (and taking hits), that aikido neglects to teach you in the name of "political correctness". The specific method matters less than getting some *alive sparring* in. Meaning learning how to hit solid objects and take hits.
--Learn the basics of police procedure. Join a neighborhood watch or student patrol (if you're near a University campus), and learn the basics of citizen's arrest, reading Miranda rights and spotting/handling forensic evidence. The idea here is that helping the police looks an awful lot like *tampering with evidence* if you don't learn how they handle the stuff, and follow their leads.
--Learn First Aid and Resuscitation. Ideally you should just bite the bullet and train to be a Licensed Paramedic--that way the law *obligates you* to be in it *helping people*. But at the very least learn the basics of cleaning and closing wounds, CPR, that sort of thing--sometimes you'll need to help victims worse than you do the perps.
--Invest in a good cellphone. One whose phone number, ideally, isn't directly connected to your civilian ID (good luck on *that* as it requires a willing accomplice). You will use it a lot when it does hit the fan.
--Invest in a good repellant--not the CS tear gas or pepper spray you get over the counter, that stuff's too weak. Check with the local laws in your area *FIRST* ok, but try to snag the stuff that the police and/or military use as "dog repellant", it's much stronger, and more likely to work against folks high on drugs and/or their own aggression.
--Invest in cuffs. This should be self-evident. Make sure they're the real deal and not "stage cuffs". Duh.
--Invest in good headgear. Not just a mask, but a helmet or skullcap worn under a hat or hood. You want something there in the somewhat likely event that someone gets a good aim on your *head* and tries to blow your brains out.
The biggest thing though is: Invest in *patience*. Any martial art takes time to learn--and some, like aikido, take years to become useful, for the trained reflexes to take. Likewise, it's going to take some time for you to gather your resources together (at least in a way that isn't going to set off red flags and paint a target on your head).
And that, as they say, is the Least You Can Do. There's more. Lots more. Maybe too much for you to handle, wouldn't you agree? ^_~
