DTP,

Welcome.

Assuming you don't have miles on any useful airline yet (if you do, you'll want to look at their cards), I agree with what folks have said here. The only thing I'd add is this:

Set a specific goal rather than just getting away a lot. You want to go to Europe twice this year. You want to go to China. You want to go to Hawaii. Whatever.

Then take an organized look at the award charts for Delta and the different Star Alliance carriers, and figure out how many miles it would take to meet your first specific goals.

Then get yourself some FF accounts, cruise the "credit card offers" thread, and start racking up the miles. I suspect you're going to want the Chase Sapphire Preferred, an Amex of some sort, and the Barclay's USAir - but you'll be best-positioned to make those choices when you know what you need to do to get where you want to go.