Before you bet the river you want to consider how many poker hands your opponents can call with that beat your poker hand. The second thing you should consider is how many poker hands will you make fold that you are losing to. If the answer to both of these questions it 0 then you should always check the river. One of the most common mistakes a player can make in Texas holdem is to bet a hand that the only people that will call beat you , and every hand that beats you WILL call you. There for there is no value in betting. However there may be some value in checking. If you are in early position and you check the hand that you believe to be a winner but by only a little, a check may convince others that nobody has anything and then they may toss out a bet to try to steal the hand. Especially if they have missed a draw and have no other way of winning the hand.
So on the river of every poker hand you want to make sure that you analyse the situation and try to think of possible hands your opponents may have and make the most valuable choice. This will prevent you form losing extra bets and be a more profitable player.