Check the chip stack
following an unexpected raise

POKER TIP OF THE DAY:
How to spot and act on a "bluff raise"

Let’s say you are holding the basis of a  reasonable but not premium hand. An opponent  hits you with a raise when it’s unexpected. Take a quick look at his chip stack before considering whether or not to fold under the pressure of his heavy bet. If the player is short stacked (low on chips) the odds are he’s trying a “bluff raise” in desperation. This would not be a time to fold. It’s a time to be aggressive.