Mandatory bets in poker are the Small Blind and the Big Blind. The amount of chips we pay for them help creating a more inviting starting pot. These initial bets are usually placed regardless of whether you have or not good cards.
One of the strategies you must learn to maintain or increase your stack is stealing the Blinds. This strategy will also allow you to increase your stack in order to keep on playing more poker hands.
To steal the blinds, two conditions must be met: the first one is related to your position on the poker table and the second one has to do with the play style of your opponents.
To steal the blinds you must be placed before the blinds. Therefore, the best positions are the Cut-off and the Dealer1. The idea is to raise the bets when no other player has bet before or if they have just placed small bets.
This increase should force your opponents to fold before the flop. The recommended amount should be of at least twice the blind.
Your strategy should focus on knowing your opponents' profile and attack them during the blinds. Throughout your poker experience you will meet passive, tight players who tend to fold rather than taking any risks, aggressive players that always pay the blinds no matter what (they will even go all-in to intimidate their opponents), and also loose players who seem to be distracted (usually because they are playing in many tables at the same time).
You will have a good chance to steal the blinds if tight players are sitting in the blinds positions. Same happens when playing against distracted players.
But you must be aware of aggressive players that may play strong during the flop to force you to fold even when they may have weak hands. If you have strong cards, go ahead and steal the blinds to double your stack.
An aggressive bet can also be a good way to steal the blinds. You may even try to go all-in if you have a small amount of chips and only few players remain in the hand.
Please remember that not all your attempts to steal the blinds will succeed, and that it is not always worth trying. For this reason, you must learn the identify the circumnstances that should prevent you from applying this strategy.
If you notice that the blinds will not increase your stack significantly then don't take a chance. Be selective and try only when the outcome would bring you a relevant amount of chips. It is also recommended not to attempt this strategy if you get to the flop without a good combination and a player has made a raise. Under these circumstances you are likely to lose the bet.