Here’s the short of it:
There are currently three different kinds of tests on the market. Given that genetics is becoming an indispensable tool for genealogists, you should probably get crackin' to take advantage of this tool. The test type you choose depends on your goals and your budget.
I have a complete Getting Started Guide that covers the test types, the testing companies, and a handy chart that helps you determine who should be tested.
Or, if you want to jump in today and order testing, I will just tell you what to do.