Even the native English speakers commonly make mistakes when it comes to using “I” vs. “me” in sentences. This is such a prevalent issue, that it is not uncommon to even find the wrong usage in formal writing or on TV. However, there is a simple way to decide when “I” or “me” should be used, which then equally applies to “we” vs. “us,” “he” vs. “him,” or “she” vs. “her” etc.
As everything in life, leaning by example works the best, and here are some simple rules of when to use “I” versus “me”:

Firstly, we have to distinguish between the meaning of “I” and “me.” Whilst the former is the first person singular subject pronoun, the latter is an object pronoun.

Thus, in a sentence, “I” refers to the person performing the action described. Here are some examples of correct usage of “I”:

Tomorrow, I am meeting Tom at the office.
The dress I chose for you is the one I like the most.
You and I will need to discuss that in private.
Betty and I have made that cake together.

In contrast to the above, “me” being an object pronoun, is the object of the action described in the sentence. Below are some examples of correct usage of “me.” Where possible, the examples given above are reworded to create a correct sentence using “me” instead of “I” to make the distinction clearer:

Tomorrow, Tom will meet me at the office.
The dress you chose for me is the one I like the most. (notice that I like is unchanged, as it refers to the subject of that statement)
You will need to discuss that with me in private.
That cake was made by Betty and me.

This seems simple enough. However, the mistakes are most commonly made when “I” or “me” is in a position in a sentence when it is unclear if it is subject or an object, or when it is joined with another noun or a pronoun.
The two examples above highlight this issue:
You and I will need to discuss that in private.
You will need to discuss that with me in private.

Although in both sentences the discussion is the action in which both parties (you and I/me) partake, in the former case, “You and I” are the subject, whereas, in the latter, subject is only “You” and “me” becomes the object.

If this is all too confusing, there is even a simpler way to decide when to use “I” versus “me.”
Try wording the same sentence by omitting others, thus leaving only I/me in and see if it works.
Here are some examples:

My mum told my brother and I/me to tidy up our room.
The options are:
1) My mum told I to tidy up our room.
2) My mum told me to tidy up our room.

Clearly, the second choice is correct, hence the correct version of the original sentence is:
My mum told my brother and me to tidy up our room.

If my brother and I/me tidy up the room, we will both get some ice cream.
The options are:
1) If I tidy up the room, we will both get some ice cream.
2) If me tidy up the room, we will both get some ice cream.
Obviously, we would never say the sentence number two, hence, the correct expression is:
If my brother and I tidy up the room, we will both get some ice cream.

That sounded like a good plan to my brother and I/me.
The options are:
1) That sounded like a good plan to I.
2) That sounded like a good plan to me.
Again, we would never say the sentence number one, leaving the first as the correct choice. Hence the correct way to say the original sentence is:
That sounded like a good plan to my brother and me.

Hopefully, this has cleared up the confusion. Whenever in doubt, refer to these examples and the chances are you will get it right! Happy writing!