The common mistakes made by players is to get married to high pairs on third street and especially having pairs in nines and kings can make you loose the game, suitable A-2-3 is good in wired queens, regardless of anything, an ace with lower cards is easier to play than using cards with higher pairs.
When holding high pair you will not know what will happen if your opponent holds a lower card? He can make two smaller pairs which can possibly beat you. If you have the highest door card in board and no one has opened ahead of you, you are supposed to go ahead and open with split kings, queens or jacks and you will win the game. Fish players can make these kind of mistakes rather than Poker Professional. Texas Hold'em Poker Rules are very easy.