A long time ago in the distant past (lol) people overused the word me, and friends of grammar campaigned to benefit the word I. As a result, people seem afraid to use me, even when it is the correct word. It's one of those things that shouldn't be a big deal, but it's super annoying.
So, how do you know when to use which? Should it be me, or should it be I?
People seem to get confused when the sentence speaks about more people than just one. Take all the others out and see how you would say it if it were only about you.
For example, let's assume I'm going to the store with Bonnie.
If I'm going alone, the sentence will be "I am going to the store." This is pretty easy, you wouldn't say, "Me am going to the store."
When adding the other person - Bonnie - you just attach her to the sentence. "Bonnie and I are going to the store."
Now, let's make this a bit more complicated.
Let's assume that Bonnie is taking me and our friend Ellie to the store. (Note, I used me in that sentence, not I.)
If it were just the two of us, I would say, "Bonnie is taking me to the store." I think that's pretty clear - you wouldn't say, "Bonnie is taking I to the store." That sounds silly.
Now we'll add Ellie to the mix. The correct sentence would be, "Bonnie is taking Ellie and me to the store." If you use me when the sentence is only talking about you, you need to keep using me when adding more people.
Next, Bonnie invites Ellie and me to dinner. Should it be me or should it be I?
If I were the only one invited, the sentence would be along the lines of, "Bonnie invited me to dinner." No one would say, "Bonnie invited I to dinner."
It's not just me, it's Ellie too, and the sentence turns into, "Bonnie invited Ellie and me to dinner."
If you're still uncertain, consider using us or we instead of specifying who is going where or doing what. Those words are harder to misuse, and you can come across as a grammar maven.