The reason I've had so much success is that I have a Newmark genealogical circle which goes back to 1800 in Telsiai, Lithuania.I have also been contacted by a distant Israeli relative that has given me yet more information.
I'm very glad I was able to find them, but there was no trick to it.When the Ellis Island and the Port of Hamburg websites came up I was able to find several relatives on the ships manifests.Finding a few on the Social Security death index, and ordering those files helped. Another thing that helped me was to find several on the NYC Naturalization Index on ancestry.com and when I ordered those documents I learned even more about the family.
Of course, the census was very helpful, but since the only two that are well indexed are the 1850 (too early) and the 1920 I had to finding the addresses which can be a formidable task. The NAturalization reports gave me several addresses and the city directory was also helpful.Then I went to an online map source, like Excite maps, and typed in the addresses to find the exact location.The hard part was narrowing it down on the census.Since I had no idea what the enumeration districts were, I had to look on many wrong pages and keep referring back to the map until I finally found myself in the right neighborhoods. Then I had to slowly close in on the exact building and tenement.It took several all day searches on Ancestry.com but I think it was worth it!
Unfortunately, it doesn't look as if we are connected.