What Use is It?
A number of things can be done and identified using genetic testing that is now available. While some is still a bit expensive the price is coming down all the time and the results are very worthwhile. There are groups to help connect you with people in your same genetic clade and determine the statistical likelihood of a relationship. This allows people of the same clade type to find relatives that they might not have previously been aware.
The first is a mitochondrial DNA test. this can tell you much about your maternal line - even which of a mere seven women all people are descended from. See this explanation and the Seven Daughters link below - which by the way is a great book.
The second - sorry for men only this one - is a Y chromosome test that can provide much information about the y-clan and the paternal line - especially if it matches and there is a same surname. Here is an explanation and this is a link to a find group's projects. A number of dedicated groups exist to assist related people who are interested in measuring their relatedness.
How to Start
Begin with a choice - maternal or paternal, or both. Do you wish to learn where you female line originated? Or are you more interested in matching up and determining familial relationships around your surname and Y chromosome (male lineage)? Both will give you immediate information about your really ancient genetic history - but contacting ancestors based on your DNA will take longer as it relies on others joining the database with their DNA samples too. That said I have been contacted by many related people in the last few months, and the databases are growing quickly as more people get interested in this method of helping to determine their roots. It is for this reason that the large databases are preferable as there is more likelihood of exact matches turning up. ftDNA claim the significantly largest database at 17 Jan 2008.
Next consider your budget - like many things there is no limit to what you can spend on your hobby. Start with a basic test which will require you to await the arrival of the kit in the mail, take a sample - usually a few cells from the inside of your cheek and then send it off and await your fist results. Often the same kit can be used for subsequent tests if you have allowed the testers to retain your DNA.
While awaiting your results, read about the various clades and their origins at the linked sites.
For the beginner with a modest budget I would recommend a basic mitochondrial (mtDNA) and a Y chromosome test which will cost you about $140 US dollars each from Family Tree DNA (FTDNA) . In this way you can begin to participate in the groups dedicated to tracking their family history and genealogy - further than ever before. If you have existing results from other services FTDNA can convert them; see special deal which may still provide a slightly more budget friendly result. FTDNA will store your DNA if required so that subsequent tests can be done without recollecting specimen and posting it. This may prove useful as new tests are developed.
Results and Interpretation
The first results you get back will allow you to determine your ancient lineage. This is what I did based on the first results I received from the National Genographic Project and FTDNA Y chromosome analysis.
Great Sites