Between you and me, I’m confused.

First, both “I” and “me” are 1st person singular pronouns.

This is a common mistake in English. Not only for English learners, but also for native English speakers. Let’s get this straightened out once and for all.

• “I” is the subject pronoun that means the one “doing” the verb. Example: I bought apples in the market this morning. 
• “Me” is the object pronoun, therefore, the object (or receiver) of the action of the verb. Example: She asked me to prepare dinner.

What to do when you face compound subjects or objects?

Compound subject and objects are two subjects or objects linked by “and”. The trick is simple. Just take out the other person so it will be clearer which one is the correct.

• Tom and me went to the cinema yesterday. (Incorrect)
• Tom and I went to the cinema yesterday. (Correct because I is the subject)
• Mum asked Tom and I to do the washing up. (Incorrect)
• Mum asked Tom and me to do the washing up. (Correct because me is the object)

What about “between you and me/I”?

Between acts as a preposition, therefore, it should be followed by an object pronoun such as me, him, her and us.

• Between you and me/I.
• Among Bill, Harry and me/I.
• Without them/they.
• According to her/she.

Which one should we use after comparatives sentences?

First, you need to be sure about the meaning of the sentences. If they are implied comparisons or not. This happens with the words so and as frequently.

1. Grandmother gives my sister more souvenirs than me. (I received from grandma)
2. Grandmother gives my sister more souvenirs than I. (I give to my sister)

It all depends if I am the subject-doer (2.) or I am the object-receiver (1.)