Tag Questions are not Real Questions

The primary purpose of Tag Questions (or Question Tags as they are also called by the Brittish) is to confirm some specific piece of information. They usually follow a statement from which they are separated by a comma. A Tag question has two components: an auxiliary verb or a modal verb and a pronoun (in that order). There is also a correlation between the statement and the verb in the tag question for if the statement is negative the verb is affirmative and viceversa. Here is an example:

You are learning English, aren't you?

She is not coming back, is she?

They can be expressed in pretty much every grammar tense.

The invasion has not been confirmed, has it?

They would love to be here, wouldn´t they?

John should not be allowed to come back, should he?

Their only purpose is not to confirm since they do not necessariñy need an answer:

Dave is the best player in the team, isn't he? (I know the answer will be Yes because I know as well as the person I´m talking to that Dave is indeed the best player in the team).

Occassionally you can replace Tag questions with other confirming expressions:

The tournament begins tomorrow, right? (Am.)

The Williams didn't arrive punctually, correct? (Br.)      

Some of them are hard to figure out such as is the case of Imperatives.

Do your homework, will you?

Don't touch anything, will you?

Notice that in this case the tag is always affirmative, regardless if the sentence is affirmative or not. Also be careful with this one because it commonly expresses irritation and could be misinterpreted coming from a foreigner.

If the expression uses Let's, then this is how you proceed:

Let's work together, shall we?

And last but not least, the verb to be in first person and simple present uses not one but two possible tag questions:

I am the teacher here, aren't I?

I am the teacher here, am I not?

Pick the one you feel most comfortable with. Me? I prefer to use Right?