I am looking for ancestors of a family of Jacob Mueller born in Cologne, Germany on May 2, 1857. He married Elizabeth Metzen in Germany and she was born Feb 24, 1865. They had three children Alex, Louis and Jack (Jacob). Alex Jacob Mueller was born on Dec 19, 1887. It appears that they arrive in the US about 1899.
Jacob Mueller also owned a Tavern in Cologne, Germany.
The family was catholic. What would be the best searches to do in order to find the ancestors?