Learning how to count cards in Texas Hold Em is a little bit different from learning how to count cards in blackjack.  In Hold Em, the dealer will reshuffle the cards after each hand, so there is no accumulation of information from hand to hand – the previous hand has absolutely no bearing on the odds of a certain card appearing in the next hand.  Also, when trying to count cards in Texas Hold Em, you only get to see your own two cards and the common cards in the middle of the table.  So, even though there might be cards no longer in play, such as the burn cards or the cards that other players have folded, since you don't get to see those cards they don't add to your ability to get an accurate count of what cards are left in the deck.

It is still worth while to count cards in Texas Hold Em because doing so will let you know the odds of certain cards coming.  Once you see the flop, for instance, you have only accounted for five cards (two in your hand and three in the flop).  However, there is still some important information that you can get from this limited bit of knowledge.  Here are the steps to counting cards in Texas Hold Em:

1. Count the number of cards you know.  You always know the two cards that you have in your hand.  After the flop you can account for three more cards.  This number increases to four on the turn and five on the river.  In rare cases you might account for another card – if a player accidentaly exposed his or her cards, for instance.
2. Count the cards that are significant to the situation.  Let's say you have two hearts in your hand, and there are also two hearts on the flop.  You want to know the odds of hitting your flush.  You need to kow how likely it is that a heart will come on the turn, and then again on the river, so you need to know how many hearts are left.  You have now accounted for four of the hearts in the deck already, which leaves nine that you still haven't seen.
3. Count the number of cards you don't know.  In the previous example, you have also seen five of the 52 cards in the deck.  So, there are 47 cards that you haven't seen.
4. Calculate the odds of certain cards coming.  Continuing the example, in order to calculate the odds of hitting a flush on the turn, you can now use the basic counts that you've done to compute the odds.  There are 47 cards that you haven't seen.  Nine of them will complete your flush and 38 of them won't.  So the odds of hitting your flush on the turn are 38 to 9, or roughly   4-1.
5. Make sure you haven't double counted any cards.  The most important thing to remember when trying to count cards in Texas Hold Em is to never double count the cards that you need to make your hand (also known as your "outs").  For example, let's say you have J-10 of hearts and the flop is 9-8-2 with two hearts.  There are nine cards that will complete your flush.  There are also eight cards that will complete your straight-four queens and four sevens.  The total number of "outs," though, is not 17 since you've already counted the queen of hearts and the seven of hearts.  The straight draw only adds six, rather than eight cards to your "outs," for a total of 15.  Therefore, the odds of hitting either a flush or a straight on the turn is 38 to 15 or roughly 2.5 to 1.

Keeping all of these principles in mind is a crucial part of counting cards in Texas Hold Em, and will greatly improve your overall poker game.  When an opponent bets it is always helpful to be able to count the cards and calculate the odds of improving your hand.  Doing so allows you to compare the potential gains of calling the bet with the odds that you will get the cards you need.