first conditional second conditional and third conditional

The conditionals are very important in the english lenguages because it is used to use in a conversations 

1. First conditional:If I have enough money, I will go to Japan
2. Second conditional:If I had enough money, I would go to Japan.
3. Third conditional:If I had had enough money, I would have gone to Japan.

Remember!

1. The conditional construction does not normally use will or would in if-clauses. EXCEPTION: If will or would express willingness, as in requests, they can be used in if-clauses.

e.g. If you will come this way, the manager will see you now.
I would be grateful if you would give me a little help.
(= ± please, come this way; please, give me...)

2. For the second conditional, were replaces was:

If I were a rich man...

3. After if, we can either use "some(-one, -where...)" or "any(-one, -where...).

If I have some spare time next weekend....or :
If I have any spare time...

4. Instead of if not, we can use unless.

e.g. I'll be back tomorrow unless there is a plane strike.
He'll accept the job unless the salary is too low.

5.There is a "mixed type" as well, for the present results of an unreal condition in the past:

If + Past Perfect - would + inf.
If you had warned me [then], I would not be in prison [now].

References 

http://grammar.ccc.commnet.edu/grammar/conditional2.htm