New and could use some help!

[Dirty Fishmonger]

Hi,
Me and my friends have decided to start a campaign and I've taken the responsibility of GM'ing. I'm not very experienced and was hoping you guys could provide some general assistance. This is what I've thought of so far:

So, the setting will more than likely be our present time, the world as it generally is today. I wanted to have them be discovered by some league or coalition of heroes and thus they join forces to combat evil throughout the world. Towards then end they would realize that their leaders, whoever or whatever gives them the orders to neutralize evil, was actually a greater evil that had them doing dirty work and they have to defeat that person in the end.
That's my general idea for the setting. I mostly have questions on how i should go about setting up the meeting-to-meeting scenarios and anything I need to be aware about such as planning, characters and things for the long-haul of the campaign.
Thanks for the help and I hope I'm not a nuisance

[King Snarf]

Well, first off, are there super-powers in the setting, and if so, what's the source? How common are they, and is the general public aware of them? That's going to go along way towards what sorts of plots are available and what kinds of antagonists to throw at the party.

[Greyman]

Is it a Spandex, Suits, or Shirts setting?

For instance:

Spandex setting: The team is recruited to be a celebrity hero team. Either government or corporate funded. They operate openly, though masked, and are publicly endorsed.

Alternatively they could be wearing sentai-themed ninja costumes, and think they're getting bad publicity for their activities against corruption.

Suits setting: The team operates in black suits, and ties; either as covert government agents or a federal policing unit (or at least they think so...). Or maybe they're a military or mercenary unit.

Shirts setting: The team is a lot more informal. They're adventurers and trouble shooters, rather than superheroes or secret agents. Perhaps they've been hired by a cryptological research institute to help investigate paranormal activity around the world; either because of their powers, or they got those powers "on the job".

[Dirty Fishmonger]

Their superpowers were going to be rogue developments based on their personal backstories that they give me. Super-powers are known to exist but rare. There will already be super-heroes and villains in existence and they will be recruited by a justice league type coalition when they are discovered. It will probably a spandex setting where they decide on some type of super-suit or outfit. I'm not going to force any type of costume on them but I'm sure they will want one. They will have masks.