Costume Design
Wa ha ha! The best part of all. Now you get to choose their physical look. They've recently added a "Random" button that designs a character for you, but if you were that type, then you wouldn't have bothered reading this far to begin with. At best, it can be useful to hit it a few times to get some ideas to start from, but that's about it.
Here you can see the various costumes I've created for Jordan Yen. Keep in mind that this is just a small amount of possibilities for just one character! There are tons of possiblities and the costume items are constantly growing as well.
Costume First
Browsing through costume pieces is a great way to design a character. When you see something that inspires you, you just go with it thinking about story and powers along the way.
Costume after Name
Building a character based entirely off a name is likely only going to happen when you are trying to create someone famous as I showed you before. Remeber if you do this, you have a chance of having your character randomly assigned a look and name by the game moderators (sort of defeating the whole purpose of putting so much thought into your design).
To pull this off well, you'd have better luck by building a character off a generic name like Internet Predator (not my idea)
Costume from Origin
Some origins lend themselves to certain costumes (Technology, Magic, Natural) and others don't (Science, Mutation).
In this case, science is obvious (lab coat and mouth cover) and the plant person seems very mutant-like, but science and Mutation are still almost always interchangable.
Costume from Archetype
If you know the Archetype, you're going to pick powers before the costume. The reason is that you will want to base the colors and costume items on the specific powers chosen.
Costume from Story
In some cases, your story is your biggest determining factor in the costume. Take for example, Blade of Nox. He was a knight in medieval England who's spirit was accidnetally called from beyond by the Circle of Thorns. When he realized what the CoT were and that they were hurting innocents, he slew them all and began a crusade to rid the city of them forever.
Costume from Powers
This can be the most fun way to determine a costume, especially one that's more "classic" in nature (read: tights). For example, in this picture you can see the same character. First equipped for fire, next for ice.