Before betting like a crazyman when you get pocket pairs (two cards that are the same like Aces or Kings in your hand), you should carefully consider all factors involved for a solid pre-flop strategy. Factors are as follows: the number of players, aggressiveness or passiveness of other players at your table, your bankroll (your chip count), your position, and how risky you should be.
When 10 people are playing, there is likelihood that someone else has a stronger hand in the pocket than in a game with only 2-5 players. Just be more cautious in larger games, because the chances of someone's pre-flop hand fitting the flop will be much greater. The more players, the more difficult the competition.
Ginen you have played several hands with one group a players for a while, and notice some A-Hole raises every pre-flop hand, you'll want to play tighter. Let the jackass win the blinds and then you can nail him to the wall when you have a solid hand in the pocket pre-flop.
If you have $5 left, you'd want to play very carefully and choose one hand to bet on to try and get as many players involved as possible for a larger pot(build the pot). An all-in before the flop is dealt is the idea here. On the the other hand, if you have $2000 at a $2/$4 table, high-risk is more acceptable which will result in high-payouts when you win.
Folks in late position can highly influence the size of the pot. So watch out for these guys. This is especially true for pre-flop. Many pots are bought when in this position particullary when the rest of the table has only called the bet.
You may want to play less or more aggressively pre-flop, depending on your style. Players shooting for larger pots and that don't mind a greater chance for losing a couple of hands will normally raise pre-flop, particularly when they are in late position. There are some that prefer to be as conservative as possible pre-flop and grinding out a winning hand once in a while. It just depends on your playing style and how perceptive you are to other players.
Consider the cards in your hand. AA is the best to start with. If your hand is suited or if the cards are sequential order like a nine and a ten ("connected"). Understanding how your two cards hold up against other combinations of cards is very important as well. There are calculators out that that can determine your odds and are very useful.