When I play poker, I imagine to myself, I just ate a very sour lemon.
My opponents are trying to guess what I am thinking, but they are confused by my twisted face.
They think I have bad cards in my hands. However, it is not! I have winning combinations of cards and my expression is just a bluff! This trick was taught to me by my personal acting teacher.
At the same time, when I have bad cards in my hands, then I act differently. I imagine myself eating a meringue cake. I have a blissful and slightly silly expression on my face.
My opponents think that I have great cards and lose.
An interesting strategy. As long as you don't go overboard, it can work.
Now you can not abuse this strategy, otherwise it can become a standard, and easily perceived by opponents.
Still, his imagination can not always work many times, especially if he meets a pro poker player because the pro poker player will know if someone is trying to bluff him or have a good card. It is hard to play with our expressions because we can forget that we are bluffing them, especially if we are really sure with our cards.
But if that strategy really works for him, he can still try to use that strategy, but I remind him always to use different strategies to confuse his opponent with your expression.