Getting a Free Card

If not giving a free card is that important, it should be clear how valuable it is to get a free card when you don't have the best hand. That free card might turn a hand you would have folded into a winner or save you a bet on a hand with which you intended to call anyway. Of course, getting a free card against reasonably good players is not easy. One way is to put in a small raise on an early round in the hope that everyone still in the pot will check around to you on the next round. Then you can also check. To make this play you must be sure you will act after your opponent for opponents) on the next round, so the play is used most commonly in a game like hold 'em where the order of betting is fixed by the position of the dealer.
Other ways of getting a free card fall under the heading of tricks and ploys. For example, you can bet out of turn to make your opponent check, which is not quite ethical but usually legal. After being reminded it's not your turn to act, you retrieve your bet, and when your opponent checks, you also check. You can take chips from your stack as though you intend to raise, and then when your opponent decides not to bet after all, you check. Sometimes just getting your chips ready to call, as though you're enthusiastic about calling, will prevent your opponent from betting. However, against top players such plays usually work only to create a bad impression, and they rarely succeed more than once or twice.