So if any action is geared towards a person/pet/something alive that someone cares about, we put "a" after the verb?
^^That is what I gather from: http://www.studyspanish.com/lessons/persa.htm
Also, something important to note from that site is that we don't use "a" after the verb "tener", or the verb form "hay", even if the direct object is a person.
Ex. Tengo dos hermanos. (tener) I have two brothers.<pre>
Hay cinco chicas. There are five girls.</pre>
Also, just like how we don't use "un" or "una" when talking about someone's occupation, we don't use "a" either.
Ex. Necesito médico. I need (any) doctor. (or) I need medical assistance.<pre>
Necesito jardinero. I need (any) gardener. (or) I need someone to tend my garden.</pre>
The preposition "a" is always used to introduce the direct object of the verb when it is considered to be a person.
This can apply to such things as pets, but not to non-specific people (as in "Somebody called a doctor.") There's also an exception for the verb "hay" and any form of the verb "tener."