Use I when you are doing the action. Use me when the action is done to you, or when the pronoun comes after a preposition like to, for, with, or between. Grammarly, Britannica, and multiple writing centers all explain the same basic distinction: I = subject pronoun, me = object pronoun.

✅ John and I went to the meeting.
Here, John and I are doing the action, so I is correct. Grammarly and the Excelsior OWL both use this subject/object logic for coordinated phrases.

✅ The manager spoke to John and me.
Here, John and me receive the action, so me is correct. Grammarly and Britannica both give this kind of object example.

✅ This is between you and me.
In formal grammar advice, between takes an object, so me is the standard choice. MLA Style explains this directly.

✅ I went to the store.
✅ She invited me to the store.
This is the clearest way to see the difference: I does the action; me receives it.

The most common mistake is getting confused when another person is added:

❌ Me and John went to the meeting.
✅ John and I went to the meeting.

❌ Please send the file to Sarah and I.
✅ Please send the file to Sarah and me.

A reliable fix, recommended by Grammarly and other writing guides, is to remove the other person and test the sentence again:

Use this quick rule:

And use this editing trick:
Remove the other name and read the sentence with only I or me.

That “remove the other person” test is one of the clearest and most widely recommended ways to catch this mistake.