Quick English: When to use 'I' and 'me'
I and me are both personal pronouns that are used when you talk about yourself. A personal pronoun is used in place of a noun when you talk about specific people or things that belong to a person.
For example, I, me, mine, you, yours, his, her, hers, we, they, and them are all personal pronouns.
When to use 'I'
I is the first person singular subject pronoun. It refers to the person performing the action of a verb. 'I' is the one doing the verb.
I am watching the Arsenal match. ('I' is the subject of 'am watching'.)
When it is raining, I like to visit the cinema. ('I' is the subject of 'like to visit'.)
Bruce and I are going to a concert tonight. ('I' is the subject of 'are going'.)
When to use 'Me'
Me is the first person singular object pronoun. It refers to the person that the action of a verb is being done to. 'Me' is the receiver of the verb.
Alexis is watching me play football. ('Me' is the object of 'watching'.)
The woman encouraged me to buy some popcorn. ('Me' is the object of 'encouraged'.)
Bruce invited Scarlett and me to his concert. ('Me' is the object of 'invited'.)
The tricky part
The most common area for people to go wrong when using I and me is when the sentence has two subjects connected with an 'and', such as "Aaron and me" or "Aaron and I". Even native English speakers often get this wrong.
The very same rules that we have already learned apply. If the people are the subject of the verb, you should use I. If the people are the objects of the verb, me is correct.
Daenerys and I watched Game of Thrones. ('Daenerys and I' are the subjects of 'watched'.)
Peter showed Katniss and me his lunch. ('Katniss and me' are the objects of 'showed'.)
A useful hint
A good way of working out which pronouns is correct in these situations is to say the sentence without the other person's name.
'I watched Game of Thrones' and 'Peter showed me his lunch' still make sense as sentences, but you wouldn't say 'Me watched Game of Thrones' or 'Peter showed I his lunch'.
In casual conversation you can usually use either and you will be understood perfectly. However, it is always best to try and use the correct grammar, especially when writing or in more formal circumstances.