Acá o Aquí?
Can someone tell me when I know to use which word in a sentence?
In theory, You would use it aca with verbs of motion However, in reality they are interchangable most of the time but some region one words is peferred over the other.
I would just add that I've gotten the impression that "ven acá" is a bit more forceful--like what you'd use if it was the third time you call someone. To convey something equivalent to "Can you come here, please?" you could say "ven aquí." But I've heard different things from different people, so this distinction may vary by region.