There isn't one. The only real way DNA test can be helpful is if you are already into traditional genealogy work using documents/records and if the company you use as cousins of your going back several generations and they are allowed to advise you of those cousins and you can make contact with them, then you can collaborate information with them.

If the company that tested you has some of your cousins going back several generations and they advise you of it they cannot tell you specifically which side of the family they come from on the overall ancestral testing using Autosoma. . However, if you have your Y tested, you get it from only one person in each generation you go back from father to son. If they have matches for your Y they can advise you but you will not know exactly how you are related to that person. He would be in your father's line but could be an uncle, a brother, a paternal cousin of varying degree such as 1st, 2nd, 3rd etc. The same with your Mitochondrial on your mother's side. you got it from her and only one person in each generation you go back. They could advise you of matches there but you would not know specifically how your are related to that person. It will be a fishing expedition.

See, you really didn't say what kind of DNA test you had. There are 4 types of DNA.

I have been trying to locate my Russian grandfather. I actually have his passport info, but it is hard to decipher. That is as much as I know about him. I've tried looking at Russian archives, but of course they are in Russian.

I just don't know where to start. Any suggestions?