One thing that I think has helped my kids ages 4 and 6, is that we have always played lots of board games since they could start to play Candy Land at about age 3. I don't let them win ALL the time. Sometimes they still get upset, but for the most part, my 6yr old son knows that we play for fun, not just to win. I say, if he has tears, let him have tears, he'll get over it. And let him know that if he is a sore looser than it makes it less fun for everybody else. I do a very dramatic role reversal sometimes too. If my kids are having a problem not winning, then if I don't win, I throw a big fit like I'm crying. They think it's funny and see how rediculous they are acting.