You want it to be unique, simple, and easy to recognize, and easy to read at a distance.
http://www.grantasticdesigns.com/logos1.htmlhttp://graphicdesign.spokanefalls.edu/tutorials/process/logos/logos.htmThink of effective logos. FedEx is a great example.

Brilliant really. What does fedex do? Get your s**t from point A to point B. Your eye is usually drawn to the red. It's no accident that only those two letters are red. See if you can see what I'm talking about with the negative space.
If they go with text, then you have to make sure the font says something about what they do.

These guys have a drippy, scary kind of font that suggests disorder. It's supposed to be hardcore. So you imagine they're that kind of band. Someone who has never heard them could guess the style of music from looking at the name with the font. That kind of things appeals to fans of that kind of music as well. (Or so it's assumed.)
I would say that you should ask them:
Who is your target audience?
What do you want people who don't know who you are to think when they see your logo?
What colors do you want?
Do you want pure symbol? Do you want pure text? Do you want a combination? Do you want altered text? (They choose one.) I'd say for a band, altered text is a good idea simply because they probably want people who don't know them to read the name. They're nobodies right now. Only Prince can change his name to a symbol and people still know who the hell he is when they are in the store.
When they give you those answers (don't be surprised if they take a long time to get it to you), then I would say to start designing anything or even throwing out ideas. Ultimately, it's what THEY want. You can waste a lot of time before they know what that is.