Hello, Kat, there may be no easy way to remember these except to use them a lot. Examples: He answered me. He said to me, "Give me one apple." I gave him an apple. He asked me, "Did you give an apple to her?" I responded to him, "Are you asking if I gave her an apple?" "Yes, did you?" he asked. I answered him, "Yes, I gave her an apple."

It is all without "to" here: He answered me. He gave me an apple. Practice makes perfect. Hope this helps, Kat! :)

I like Scott's examples. There is no difference between #3 and #4. In #4, "me" is an indirect pronoun so it means exactly the same as "to me". #1 and #2 are more difficult to analyze. I interpret "me" in #2 as a direct object. That is, I interpret it as saying that "me" is whom was answered. In #1, you are giving the verb an indirect object "to me". I think it sounds bad. It's not incorrect, but I if I wanted to say that he answered a question and delivered that answer to me, I would say: "He answered the question for me".

‘To answer to someone’ is correct, but it has a different meaning than ‘to answer someone’. I answer to the CFO. (He is my supervisor at work) We answer to the shareholders. (We are working for them) The mayor answers to the voters. In these cases, ‘to’ is correct but it has a completely different meaning than when it is left out.

This is called the "dative case": https://en.wikipedia.org/wiki/Dative_case Unfortunately I cannot find a list of dative verbs in English, but, for comparison, there are approximately 50 in German.