概念上来说,如果要找的是确定的东西/人,那么宜用find,例如：
The king sent his men to every part of his land to find the princess.
国王派人四处寻找公主的下落.

如果是个非具体的囫囵概念,宜用look for,例如：
The king sent his men to every part of his land to look for something delicious.
国王派人四处寻找美味的东西.

好好体会比较一下.