The suit needs to be armoured, bulletproof and with chainmail to deflect blades. Made in panels so when damaged, they are easy to be replaced without having to replace the whole suit. A two-way radio to your support team that is very close by. Skills should be martial arts like KFM, others depending on what you plan to do-Batman needs things like lockpicking because he breaks into buildings. Personality is not that important-that being said, don't waste time on being a smartass like Spider-man, the bad guys don't wait for a soliloquies to finish. Unfortunately, life isn't like the comic books. As Kyro says, vigilantes get arrested, no matter their good intentions. The costumed heroes are well-known to the local police, and watched. Otherwise, they walk around town giving out blankets and meals to people who need them. If a local vigilante evades the police, trust me-it's a fluke.
All us nerds have wanted to be a costumed crimefighter at some point, but the reality is, it's just not that feasible. But, we can all be heroes in our own way. The vigilante idea will only come to no good.
That's my thoughts on the matter. People can agree or disagree, they are just my opinions. Oh yeah, he needs a crap-ton of money, as well.