|Why raise pre-flop
The pre-flop raise indicates the strength of your hands. The raise ensures that the hand that you make a strong case for other players to be cautious of what you have. Of course, not all your opponents will believe that you have a strong hand, and will not be pushed over.
They may in fact believe you are bluffing or that they have a stronger hand. The best way to deal with this is to reinforce the impression that you have a strong hand.
After you play the flop, you might run into the situation where the three community cards that are face up do not really add to your current hand. This might be depressing, but if you have no intention of throwing away your hand then you have a choice to play on. The community cards after all, may not have helped out your opponents either and they may still hold worse hands.
If you have an ace and a king in one hand, and the flop draws a 2, an 8 and a Jack. This might mean that you want to make a continuation bet. This will be a show of confidence in your cards, and if you are holding a weak hand, you opponents may believe that you are holding a pair and you are not worried about the flop.
This can result in you winning the pot without having to go any further. Your opponents may on the other hand be holding jacks and with the flop hold three of a kind. They will certainly not be going anywhere.
He who laughs last, laughs loudest
The continuation bet is more effective if you are the last person to act. When you are the dealer then you can see if any of your opponents have indicated that they have good cards. If there is no player who is showing strength, then now may be the time to get them to fold. When you are first to act, there is more chance of being called and comes with more risk.