Because the blinds will start to become larger and larger in relation to your own stack of chips it is important that you do become involved in the action before you start to get blinded away and that you don't allow your stack to become so small that your bets pose no threat to your opponents.
By the middle section of the game you will need to be increasing your number of chips and to do with you will often need to start constructing hands or stealing blinds from your opponents. In short you need to make things happen for yourself if the good cards have not been coming your way. As the game develops more and more players will be eliminated and you need to identify which of those are passively trying to get into the money and try to steal from them.
Remember, the only thing that matters in a Single Table Tournament is that you get into the places which pay out a prize and all of your efforts should be focused towards that goal. Don't expect that players will knock each other out, especially if you're the lowest stack left, and always be ready to make your move. Nobody wants to be the bubble and miss out on the money by one place, so a bold approach will often bring its own rewards.