Not tipping your hand (to continue the theme) to your players is always an important consideration, and being able to maintain a neutral expression is very handy. My poker face is pretty awful, although I sometimes thing it’s working well. I’m sure that over the years my players have been able to read my expression just fine even when I thought I was being sneaky.
I’ve never considered practicing my poker face, though, and that’s what this article advocates. My favorite tip is this one: don’t show your teeth.
Keep your lips together, but not tightly, when showing your poker face. The mouth supports your whole facial expression, and, if you can control your mouth, adopting a good poker face is much easier.
That sounds like a pretty easy thing to remember during games, and a good start towards perfecting your poker face.