I have been working on an interesting case of late and I think it provides some clues for searching for others.
A while back someone posted here in he discussion group looking for help. The situation was they had a 1906 NY passenger list arrival with a Polish name going to a person in New York with only a first initial and a family name and an address. The person they were going to was listed as an in-law. The poster of course was trying to track the people.
The in-law name was too common to search especially with just a first initial.
The obvious first step was to try the address and no one with that name was there in 1905 or 1910. Searches using the Polish name in the census came up blank too.
City Directories were of course a possibility but again it had to match on the address to work.
I got super lucky playing the the Polish name. I found a woman arriving in 1910 with the same Polish name going to her husband. Still nothing on the Census with the name but she gave an address for the husband. She was arriving at the end of 1910 but I still worked the address backwards and ...
surprise surpirse who was living at that address even in the spring of 1910 but the husband who had changed the Polish first name to an American first name and he was still living with the in-law. Now I had the in-law's full name and the husband in America!
It took some more maturations but I picked up their trail in the census or at least the family I thought they were. Challenge was now to connect all the dots.
I found one of the children or at least what I thought was a child who died at age 19. Found his grave in one of the old off-line cemeteries but not the parents. But I have the name of the cemetery and the burial society.
I picked up a possible target for the father having died in 1939 and I checked the certificate while I was at the Archives to get the cemetery but there was nothing to confirm it was the right person. The father's name on the certificate was Americanized. But I had the cemetery name and the date. So I called that cemetery and checked on the grave. The man is in a double grave with a wife of the right name too. And it is the same burial society as the person I thought was the son -- just a different cemetery.
So off I went to the cemetery and found the grave and got the Hebrew and sure enough the Hebrew on the stone matches the Hebrew name that was expected to place this as the man who arrived in 1906 with the right father's name back in Poland.
Case closed / solved. Maybe not the most amazing find but some good detective work. The person was found. His family line was found. The names nd married names of his children were found. And the mysterious in-law was found and could also be followed.