1.2.5 Conditionals

We use conditional sentences when we talk about things that are not certain, have not happened yet or when we imagine a scenario. Conditional sentences consist of a conditional clause and a main clause, and most common types always involve if or an if-clause.

Zero Conditional: we use the Zero conditional when we talk about things that are always true; the present simple is used in both clauses.

"...Sally Draper, come over here this minute. If the clothes from that dry cleaning bag are on the floor of my closet, you're going to be one sorry young lady."
You piss off Betty, you will pay, that's for sure.

If you don't like what is being said (if-clause), change the conversation (main clause).
For Don, this is always true.

First Conditional: when we talk about real, possible situations, we use the first conditional. The usual formula for this conditional is if + present simple and will + infinitive, but it is not important which clause comes first.

"I'll tell you the same thing I told my daughter, if you put a penny in a jar everytime you make love in the first year of marriage, and then you take a penny out the jar everytime you make love in the second year, you know what you'll have? A jar full of pennies." - Roger Sterling
Or:                         If you put a penny in a jar [...], you will have a jar full of pennies.

Second Conditional: the second conditional is used to talk about unreal or impossible things. The typical formula is if + past simple and would + infinitive.

If you were me (if-clause), what would you do?

If I could get Betty in the ground (if-clause), I would stay here until 1975.

If i did not know you could (if-clause), I would not do this.

Third Conditional: this conditional is used to talk about the past and situations that did not happen. The regular formula for the third conditional is If + past perfect and would have...

If i had found a gif, this post would have looked better.

Sources: http://learnenglish.britishcouncil.org/en/quick-grammar/conditionals-1
http://dictionary.cambridge.org/grammar/british-grammar/conditionals