Cops, soldiers, detectives, undercover agents, fire-fighters, rescue workers, first-responders, volunteers, etc do this kind of thing all the time. They do it without costumes, then again costumes don’t make you heroic.
Of course cops and so forth are paid to do this, but the pay is usually meager to say the least (and certainly does not compensate for the level of danger and risk involved, and often doesn't even pay for decent equipment/gear), if you're in the field anyways.
Here is my opinion on these matters, based on my own experience. Take it for what it is worth.
I understand the allure of the Lone Wolf Vigilante. (I use vigilante here in a limited sense, as in what was once called a Regulator or Militiaman, not someone out to “take revenge or the law into his own hands, and do whatever he wishes to keep the peace.”)
And personally I’m not against it, I’m all for individual citizens being/becoming Vigilantes. (As the Roams would have thought of it, and as the Frontiersmen of America would have thought of it – the Romans would have traveled in teams as Vigilantes, the Americans in small groups or as individuals).
The Vigilante has the advantage of being able to be where the police cannot be (the opposite is also true), due to the fact that there simply are not enough police. (I’ve done this kind of work myself as both an undercover operative on assignment, and as private citizen on patrol on my own initiative – and I still do on occasion). Also you can work on your own projects, like crime anticipation and suppression (rather than just incident response), community security, criminology projects, non-lethal weapons development, and so forth. You don’t have to worry about being approved for clearance by your office or agency, or funding requests, because it’s self-funding (though there’s your real problem right there, isn’t it).
The disadvantages to the modern Vigilante (assuming he operates lawfully and not to do whatever he wishes) are these: it is an expensive and self-funded operation, except in certain limited circumstances he has no power of arrest (but he can interfere to prevent harm and crime) merely observation and tracking and reporting ability, it can be dangerous (especially if done stupidly) and you have no support or backup. These are very real disadvantages that the Vigilante must compensate for, through various means.
This does not mean the Vigilante does not have his place and is not potentially a valuable asset for peacekeeping, crime prevention, rescue work, even emergency medical aid, and so forth, but the idea is more romantic than realistic (as far as most others are concerned), he has his limitations. Real ones. But that doesn’t mean that, properly operating, a vigilante, or a group of them, cannot be helpful to local law-enforcement, to other agencies, and to individual citizens.
Personally though I’m against the “I’ll put on a crazy looking costume and go out and patrol the streets” (or whatever it is you take up as your function). Because crazy looking costumes are usually more dangerous than beneficial, and one should never mistake will and desire and comic-book inspired heroism for actual field experience, training, and long hard hours of real preparation and study. There is nothing wrong at all with will and desire, they are fundamental to achievement, but they should in my opinion always be tempered with study, training, patience, experience, and real work.
That being said I’m not against suits. (I have several, and they are very useful, but there is a reason the operational suit of a SWAT member or soldier or, in some cases the suit of an agent, is designed as it is, because long experience has demonstrated how it is actually useful. This doesn’t mean suit design can’t be improved, it merely means suits are far better than mere costumes.) So a vigilante’s suit can be helpful (whereas a costume will likely not be), but to be honest, both suits and costumes arouse far too much suspicion if you’re actually spotted in one. By far the best way to operate, day or night, is in simple street clothes, or disguise clothes appropriate to the environment you are operating in, with a simple backpack or carry bag containing the actual equipment you might really need.
As I said I’m not against the Lone Vigilante at all. But I strongly suggest he/she get trained in a wide variety of useful skills (rather than stupidly learn by trial and error and by exposing himself and others to unnecessary and reckless danger) - and there are a number of governmental, public, and private organizations that will give you such training, at least on the basic level, that he study, start very small, get plenty of actual experience, and go about the effort as if he were a professional (even though the effort will be amateur and probably unpaid) rather than a game or a hobby. Because he protects himself that way and helps others that way, learn as you go about and in dangerous situations is a fools errand.
Also if he joins some good organizations to receive the proper training then in case of real emergency, like terrorist attack or fire or natural disaster or plane crash he will get called out on a volunteer basis with other trained volunteers and with paid professionals to assist in an organized and methodical way, rather than operating without any real idea of what the real situation is.
In normal circumstances, and in everyday situations he can pursue his own Vigilante activities, within the law, as a lone or singular operative. But in a real crisis he will far more likely than not serve better as a team member at a group effort.
Also I should say a few other things based upon my own experience of nearly 35 years of doing this kind of thing: Have a plan, a real one. Know exactly what you are trying to achieve, like a 50% reduction in violent crime in a particular area, or suppression of math labs on a particular patrol beat, the tracking of gang activity, a reduction of drug smuggling operations through your county, or helping to solve cold cases, etc.
Going out on patrol, just to see what happens, is interesting, and sometimes outright exhilarating. But your odds of being truly useful in this way are slim. (Though on unorganized patrol I have helped put out fires, rescued a kid from a car wreck one time, discovered gang nests, found a chop shop by accident, uncovered a multi-state drug smuggling operation, and have recovered lost or runaway kids. That may seem impressive, on the surface, but that’s over years and years. It isn’t cost effective or useful on an on-going basis. Planned patrols and organized anti-criminal or rescue activities are far more fruitful.)
Instead have a plan, know how you can actually be useful, set out with a goal, establish good relations with the local cops (maybe as an informant, known or covert), study, train as much as possible, and be creative and experimental.
Going out on patrol is fine and all, and sometimes can be useful (if you carry a multi-band radio and have good beat maps) but in all honesty, it is usually wasted time and effort. (Though I do know people that this is all they wanna do, then again they usually waste their time and haven’t prepared for much.) I only go out on unorganized patrol once or twice a month, and it isn’t really unorganized, I know exactly where I want to patrol and why.
But if you have plans and goals and objectives you can be useful, and you will mitigate the risks to yourself, and greatly increase the odds that your own training and experience and study will actually be helpful to others in a practical and beneficial way.
And here is my list of what a good Vigilante should study and learn about and train for, though this list is neither exhaustive, nor does it exclude anyone, it’s just my opinion: CPR, emergency medical aid, tracking, basic detective skills, equipment and tool use, emergency/disaster response, basic police procedures, communications, basic criminology and criminalistics, survival skills, surveillance, escape and evasion, and defensive and evasive driving. Knowing the secondary languages common to your area are a good bet nowadays too.
Anything above and beyond that is very good and helpful. I’d also suggest having good, reliable equipment, whatever you can afford, get the best training possible, study on your own often, and undertake the effort professionally rather than haphazardly.
I actually encourage citizens to become Vigilantes (in the sense I described above, with the caveats above), but it never works like it does in the comic books. Nor should it work like it does in the comic books. Comic books are comic books, real life is very, very different. And far more dangerous, and in my opinion far more important than any fiction. So Vigilante activities should be undertaken as if they are important activities that you train and plan for, not spur of the moment, “boy that looks cool” adventures.
(I’m not saying that anyone here has that motivation, I’m merely saying that’s a very poor and dangerous motivation for such work.)
