How can I find a lost relative?

Question:

How can I find a lost relative?

My greatgrandfather immigrated to the States in 1914. My father's family had no idea if he had ever reached New York. That is up until 2 months ago when I was able to trace him in the Ellis Island passenger records.
However, I didn't manage to find anything else. Can anyone give me a clue of how I can find more info?
Of course he is not alive, but it would be cool to find his offspring!

Additional Details

4 months ago
I' m positive he changed his last name. I say this because since I got your answers I've searched all sites and couldn't find any info about the name I gave. It's logical if you come to think of it. The name is not easy to pronounce in English.
So, what else can I do?
P.S. Thanks for your support.

Best Answer - Chosen by Asker: 4 months ago
I' m positive he changed his last name. I say this because since I got your answers I've searched all sites and couldn't find any info about the name I gave. It's logical if you come to think of it. The name is not easy to pronounce in English.
So, what else can I do?
P.S. Thanks for your support.