Once the game has started and the cards have been dealt. This is a critical time in the game as you will need to decide if the cards are worth playing.

Basically you should play with any two high cards i.e. 10's up; Ace and 9; or any suited cards with an ace, and pairs are usually played from 7 up.

High consecutive same suit cards e.g. 9s, 10s (spades) and lower pairs can also be played depending on your position and the following factors which are general points to consider before playing the hand.
Number of players C in a 10 player game chances are someone will have a strong hand and you'll need two high cards (jacks up) or a high pair to play.
Your bankroll C if you are about to be called "all in" choose the hand you play carefully if you have one last hand you want it to be a good one.
Others playing aggressively - assuming some amateur players tends to raise constantly, let him win the blinds, wait for a good hand and press him to the wall.
Your position C as mentioned in the last lesson, when seated in a later position play more than in an earlier position.
Remember that the key to becoming a good player is to have patience, a player that tends plays a lot of hands will eventually lose.