“Follow the money card.”
That is all you need to do to win.
As far as gambling card games go, the Three-card Monte is just about the simplest game you can find.
There are three cards, placed face down on a table.
One of the cards is the “money” card, usually the queen of hearts. The other two cards are knaves—the jack of spades and the jack of clubs.
The dealer shows you the money card, places it down again, and then quickly rearranges the cards.