Welcome to CoH!
Long before you get into the tutorial (which I think everyone new to CoH should run through at least once just to get a feel for how the controls work and how your character's play) there is the character creator. Depending on what you have in mind and how much you want to work towards the 'perfect look' you could easily spend 2 hours just creating your character's look and the colours of your chosen powersets. You can actually do this while the game is still installing. While you are in the CC (character/costume creator) the tutorials will be installed, and after that the game itself is installed. If you want an idea of how varied the costumes can get, head down to Post your best costume here to see what others have created. One of the things I love about CoH is that unlike other MMO's, your costume has zero impact on your character's abilities. Your powers are enhanced directly with your 'gear' in the form of, wait for it... enhancements.
@DougGraves gave pretty good suggestions on character archetypes to start with depending on if you want to play melee or ranged and @Techwright gave a pretty comprehensive list of things to be aware of.
I just like to add, once you get in the game proper don't be afraid to ask questions. Oh and another thing, you can play on 1 server or all the servers and your limit on characters is basically your own imagination. While Excelsior is the highest pop server that also comes with it's own drawbacks. Heck, make a character on every server and check out the community on all of them to find one to your liking.
Once again, welcome!