About halfway through a $340 no-limit hold 'em tournament, I was in the big blind when action folded to the cutoff (the first seat to the right of the button), who merely called. Just calling preflop in that spot with so few players left to act is always incorrect. It was an especially glaring error for this player, since he had only 10 big blinds remaining in his stack.

I see mistakes like this in every live tournament that I play, and it's obvious that many players still don't know how to play a short stack in tournament poker.

It's usually bad to limp preflop. People limp because their hand isn't very good and they want to see a cheap flop, hit it hard and get paid. That is completely counterintuitive to advanced poker theory.

What's the goal in poker? Make the best hand. Put more money in the pot. When you don't have the best hand, put as little money into the pot as possible. Figure out what they have. Don't let them figure out what you have.

This player called. From the cutoff. With a tiny stack. Why?!

He put as little money as possible into the pot because he knew that his hand was speculative. If one of his remaining opponents raises, the cutoff won't have an idea what sort of hand he's up against: The opponent might have a real hand, or he might be picking on the cutoff for limping. Conversely, the cutoff's hand is easy to read: He's already signaled to his opponents that he doesn't have a hand good enough to raise nor a hand bad enough to fold.

When stacks get shorter in tournament poker, it's time to look for spots to go all in. If you're not in a good spot, fold.

This hand came with blinds at 1,000-2,000, plus an ante of 300, and nine players at the table. These numbers determine m, which is the cost of one round at the table. The blinds are worth 3,000. Add the 300 ante for nine players, and that's another 2,700 for a total of 5,700.

My opponent had open-limped from the cutoff with a stack of 20,500. The button folded, the small blind called, and then it was my turn in the big blind. There was 8,700 in the pot. I knew that the cutoff didn't have anything. I knew that the small blind didn't have anything. I knew that if the cutoff called a raise from me, he'd be committed to the pot and would likely go all in.

I looked down and saw Ad 6h. I raised to 6,600, and both players folded. But I would have raised with any two cards because of the information provided to me by my opponents, and I would only have been risking 4,600 more to win the 8,700 in the pot already.

Tournament players should never open-limp and rarely open-raise if they have an m of less than 5 and would fold to a preflop raise. It's much better to go all in preflop. Had the cutoff gone all in and won the pot without a fight, he would have increased his stack by nearly 30 percent, and that would have bought him another round to find a good spot. Instead, he gave away about 10 percent of his stack and never saw another card for it.

Be aware of stack sizes in terms of big blinds and m. With a stack of less than 20 big blinds, a player should be looking to get all of that stack into one pot rather than seeing flops and playing hands. With a short stack, there is no room to maneuver or collect implied odds. Don't be afraid to go all in with weak hands, because when opponents fold, it doesn't matter what your hand is.

Bryan Devonshire is a professional poker player from Las Vegas. Known as "Devo" on the tournament circuit, he has amassed more than $1 million in career earnings.