Re: Could this be a correct explanation for Object Pronouns?
I am not a teacher and I don't pretend to be, but I think I would understand better if you focused on the ROLE the pronoun plays in the sentence (as Bruna says, is it the "doer" or the "receiver" of the action, directly or indirectly) and not tell them to look for cues like "what sort of word comes before or after it."
When you consider how many words in English can be both a noun and a verb, and also things like inversion, simply picking out words to serve as signposts is not going to be helpful in the long run.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.