Step 3: Deciding what to wear
One thing you need to come to grips with, post haste, once you decide to take the plunge into superhero status: your crime-fighting clothing will make you look like a refugee from a gay pride parade. There is no getting around it. Tighty-whitey underwear (of whatever color) worn on the outside, some sort of large belt, spandex shirt and leggings, and some ridiculously-high boots are all staples. The only flexibility you will have are in choice of color, whether or not to go with a cape, mask vs. no mask, and whether or not you'll wear gloves and a hat.
You have to be smart when you accessorize. Superman went glove-, hat-, and mask-free. So he simply had to go with a cape, otherwise, he's just a fool in a leotard and under(outer)wear. I am sure if you were to ask him about it, he would express regret over the decision and would have put the gloves on. Now, if you're, say, Bat Man, and you need the cape in order to fly, then you have no choice. But judging by today's sensibilities, unless you are Liberace or one of the members of KISS, think long and hard before you go with a cape.
Step four: Sidekick? Or lone wolfing it?
Are you going to go at this thing alone? Or would you like a hand? Before you answer, know this: if you make the wrong choice, it could be disastrous. If you are always making stupid decisions and need to be bailed out by your monkey sidekick on a regular basis ("Shape of shoe horn!" "Form of an ice cube!" Yeah, I am talking to you, Wonder Twins) then you definitely need someone watching your back. But if you like to go your own way like Wolverine, a companion can only get in the way. Worse, he can cause all sorts of mayhem. While not technically a superhero, Scooby Doo had two completely useless sidekicks in Daphne and Velma. The former was always getting taken captive by the monster while the latter was constantly on all fours, feeling around in the dark for her glasses.
Nobody wants a needy sidekick. In fact, most superheroes do not need a junior partner of any sort. After all, what is Bat Man without Robin? He's still freaking Bat Man! But what is Robin without Bat Man? Squat. But, be advised that if you are presented with a willing partner, think twice before dismissing him out of hand, as you may just be laying the groundwork for your own demise. Recall that Mr. Incredible spurned IncrediBoy's offer of help and it nearly cost him his family. Bottom line: be smart about this decision. If you want to take a cue from the Fat Kid...he doesn't have a sidekick, per se, but could really use one because he is always running out of nachos and could use someone to run to the store so he doesn't miss "American Idol."
Step five: Your secret identity
Unless you're Santa Claus, you don't live and work in the same clothing and personae. It could get you killed, or worse, you could be hounded constantly by autograph seekers and bill collectors. So, you need to hide your true identity while you are not fighting crime. But how should you do it? The two current schools of thought are: 1) Nerdy and Forgettable and 2) High Profile and Hunky. Nerdy and Forgettable lets you hide out in plain sight, overlooked and underestimated. Clark Kent and Peter Parker are guys you'd look past and never even think they were capable of leaping tall buildings in a single bound. It gives them the freedom to go where they want unnoticed. That's cool if you don't want women to ever give you the time of day and desire no social life of any kind. But if you like to occasionally go out on dates, you may want to consider the High Profile and Hunky route. Bruce Wayne is a billionaire playboy who has hot tub parties with super models while vacationing in the south of France. He hides on the front page of the social papers, banking on the fact that nobody would ever think a cool cat like that would dress up in his pajamas and beat up bad guys. So, nerdy reporter or uber-rich chick magnet? You'll have to make that tough call on your own. For what it's worth, the Fat Kid has always assumed the nerdy chess player secret identity, even long before considering crime fighting as a profession. That's what we in the business call "deep cover."
Step five: Building your secret hideout
While it is not an absolute requirement if you are a good guy, a secret lair/lab is a must for the evil doers. Bat Man has his Bat Cave, wherein he tinkers with his props and monitors the happenings of his arch nemeses as well as his many, many girlfriends. Superman has his Fortress of Solitude, which (for some reason) is at the north pole. He should rename it the "Fortress of Freeze Your Butt Off," because the only useful thing about being that far north is that you are outside the blackout zone of every major sports team and can get their home games on television whether or not they sell out. If you are like Spider-Man and are too poor or too cheap to build a secret hideout, you can always hang around the Halls of Justice, where the Justice League (or was it the Super Friends?) meet. If people ask why you always seem to be there, just tell them that your secret lair is getting fumigated because of a termite problem, so you need to crash at the Halls of Justice until it's safe to sleep at home. Unless it's Wonder Woman and she has that rope tied around you, they'll probably buy it and leave you alone.
If you are a bad guy, you have to spend every penny you steal on a high tech, super elaborate facility, with death rays, a tank full of man eating sharks, and a ginormous television that will show you anything you want to see - especially if it is Aquaman being slowly lowered into a volcano, bound and gagged and dangling by his feet. Of course, you will never actually watch your evil plan come to fruition, because you will just assume that your evil contraption will finish lowering Aquaman to his death so you get in your super secret rocket ship and fly away, and when you do that he will escape and foil you. You spent all that money on the television - would it kill you to spend another two or three minutes making sure that your plan to kill Aquaman comes to pass? Please!?!? Don't forget to place your secret lair on a remote island that is shaped like a skull. That is a requirement if you are evil.
Step six: Your name
Some would think that naming yourself should be step one, rather than the last step. They would be wrong. After all, you are really, really limited in what label you can place upon yourself. After all, if Spider-Man weren't Spider-Man, what else could he be called? I know that he chose "The Human Spider" as his name, but let's face it, that was kinda lame. So, Spider-Man was really the only thing he could be called. So, to name yourself, basically go one of three routes: 1) Color + Object/Monster (Green Goblin, Green Lantern), 2) Synonym for "Good" + Man/Boy/Woman/Girl" (Superman, Wonder Woman, Wonder Twins) 3) Some descriptor of your superpower, with the optional "Man" or "Woman" at the end. (The Flash, Plastic Man, Storm, Aquaman, Fat Kid).
So, there you have it. Everything you need to get started with your life of crime/crime fighting. Once you get into it, you'll find you need to add some details to give it some pizazz. Like you'll have to come up with a catch phrase. Superman has "Up, up and away!," Shazam has "Shazam!" (not the most original catch phrase) and the Fat Kid has "I'd like a refill." If you're a bad dude, you should work on your maniacal laugh and consider having some sort of lap pet which you can stroke menacingly while you describe your evil plans to whatever superhero you have captured. There are other nuances, but I think you get the idea.