What happens when you mix two colours? You get another colour. It's a fact, and we use Type 0 Conditional to talk about the things that always happen: If/When you mix red and yellow, you get orange.
What will you do if it doesn't rain this weekend? It's a possible situation that can happen in the future, so we use Type 1 Conditional.
What would you do if you had a lot of money?
What would you do if you were a president?
What would you do if you visited the USA?
These are all imaginary situations in the present, and we use Type 2 Conditional.
