1: Don't Be afraid of what is in front of you, be afraid of what is inside of you, if you trust in the strong points you have within you you then you will have faith in them and that they can lead you to winning what ever price you want.Again don't let what is outside of you be little what is inside, don't be deceived by the outside factor, always trust that the inner factor is greater
2: Do not listen to the nay sayers, David ignored those who said he can not defeat Goliath, nay sayers have the potential of killing the believe that you have for the power within you, so if you give time to the negatives they say, you might end up loosing the believe you have inside you.
3: Win before you even start, David went to that battle with the spirit of someone who had already one. In other words, he had conquered the battle in spirit before he did so in flesh.He also conquered it by heart so when he got to the battle he delivered the same results. The Great Boxer Muhamed Ali also used this trick, he will tell his opponent how he(Ali) is going to win a game and when the game comes the very same thing he(Ali) had said will be the result.
4:Don't take more arms than you could carry, More arms can be a burden for you, so you need to take whatever arms that you think will best work for you and will eliminate the opponent quick and easy, you don't want to fight long fights because you might be more tired than your opponent.
5: Be willing to put a sacrifice, David gave up a huge sacrifice, which was his nation. His nation was going to serve Goliath nation if David was to loose the battle. This sacrifice gave him a boost to his commitment to defeat Goliath, Defeating Goliath was the only thing he was to do because he could not stand loosing his nation. So sacrifices boost our commitment, they make us will more to win.