Lo ciento no habla espanol. Look for, is like you lost something, and you trying to find it. Ex: I lost my cell phone, I have to go look for it. Look up, is like doing research. Ex: My friend just asked me what the longest word in English is. Now i have to go look up the answer. I hope I helped.

Well worded question Raul! :D

"look for" se utiliza para buscar algo o a alguien... I need to look for a job, I will look for you... "look up" se utiliza para buscar en libros de referencia (diccionarios, directorios, listas, etc.) ... I looked up the meaning of the word, look me up on Facebook. Una frase muy comun es: Look me up (when you're in town)... es como una invitación 'buscame cuando visites este lugar'. Espero te ayude :)