If you're starting from scratch, you might want to beef up a bit of your knowledge about credit:
http://creditboards.com/forums/.
Assuming for the moment that you have credit scores that can bear applying for several cards at once, I think it's a good idea to keep goals in mind, such as where do you want to fly, in what class, and who flies from your airport? Those questions aren't as silly as they first appear. Although you can ultimately fly on a number of carriers using a number of rewards miles from airlines that might not even fly from your local airport to your desired destination, it's always a good idea to identify your travel goals.
Then, try to figure out which airline (or alliance) helps you get there. If you have several good options from your airport (and most of us do), then look through the various airline threads here at FT to get an idea about awards availability. The short hand answer: American's not bad, Delta seems pretty iffy (except, possibly, for short-notice redemptions), and United/CO seems in between. British Airways has generally good availabilty, but taxes and fuel surcharges may offset the attractiveness of the use of BA's miles. There are plenty of other airline options; use the FT boards as a resource.
I understand the information overload. Keep in mind that you have plenty of time to answer these questions. Believe me, if you have good credit, you won't focus on just one card. I'd suggest you spend a week poking around FlyerTalk--keep looking at the MilesBuzz forum, but look also at the credit card and airline threads. Looking at the hotel threads is also not a bad idea.
And there are some internet resources that may also focus your thinking. A few suggestions:
http://thepointsguy.com/
http://www.frugaltravelguy.com/
http://boardingarea.com/blogs/viewfromthewing/
http://millionmilesecrets.com/
http://www.freefrequentflyermiles.com/index.htm
http://www.onlinetravelreview.com/
http://boardingarea.com/blogs/onemileatatime/
http://boardingarea.com/blogs/loyaltytraveler/
That should keep you busy for awhile. Keep reviewing the threads here. Don't rush into any decisions. Keep an open mind. Understand that conclusive statements, such as "SkyPesos are worthless," may be true for many--but perhaps, not for you. The research is worth it; just ask a fair number of people who hopped on the BA 100K deal and then discovered that for many routes, BA's fuel surcharges made the deal look a little less attractive than it first appeared--although the program has many features that I personally very much like, and I have no problems with the surcharges.
Here is a list of cards that might be worth your investigation, but this is certainly not an exhaustive list:
http://www.flyertalk.com/forum/miles...t-2-first.html
http://www.flyertalk.com/forum/miles...0k-points.html
http://www.flyertalk.com/forum/ameri...-up-bonus.html
http://www.flyertalk.com/forum/miles...-open-all.html
http://www.flyertalk.com/forum/miles...romo-back.html (for this one, the 100K promo is expired, but there's currently a card with 50K miles out there).
That's a lot of work to do. One helpful pointer I follow in reading any long thread: read the first couple of pages and then look at the last three to five pages. The first couple of pages will give you the general outlines of the deal and many times a web link; the last few will give you the current landscape of the deal. Many of the intervening pages, especially in threads hundreds of pages long, contain repetitive or expired information. The thread on the AA cards is especially well maintained--definitely follow the instructions in the title that direct you to read post #2 first.
Good luck. In six months, you'll probably be asking yourself, "so where do I get my next half million miles?"