I have decided to have my DNA tested.

I have been searching my family tree for a while now. I have no problem searching on my mother's side. I can clearly see when my relatives came over from Germany in 1927 durring the economically difficult times between World War I and World War II. However, my Dad's side of the family has proved more elusive. I can trace the family back to 1845 in Tennessee. After that the trail goes cold. I have no leads.
This had lead me to try DNA testing to see if that might shine more light on my elusive distant family members. I researched the four main players in DNA testing. AncestryDNA, 23AndMe, FamilyTreeDNA and NationalGeographic Geno v2.0
After a bit of research I settled on FamilyTreeDNA as they have projects that compare your DNA to others with the same family surname.  This helps to give more accurate results as your results get compared with known histories of other people with the same surname. I chose to do the Y-DNA test that only looks at the father's y chromosome. You can read more about DNA testing and the different services and their pros and cons here, here and here.