From the same article:-
1. Since children who are sore losers often have unrealistic expectations of themselves, one of the best things parents can do is to help them set goals that emphasize effort and improvement, as well as winning. Those goals might include passing the basketball well during the pressure of a game, or swimming two lengths of the pool nonstop.
2. Look at the subtle messages you're giving your child about failure. Many of these are unconscious and therefore very difficult to recognize. For example, if you have a big celebration when your child's team wins a game, but you just say, "Well, you tried," when they don't, you're teaching that you value winning much more than effort.
3. Talk to your children about some of your own frustrations. Sore losers often worry that anything they don't succeed at will be shameful to their parents. This concern is compounded if they never see or hear about how family members handle disappointments. Don't feel you have to talk only about sports. Discuss how it felt when you didn't get the lead in the school play or when you got turned down for a job you really wanted.
4. Let your children practice losing as well as winning. Consistent winning of games at home may set up unrealistic expectations for when they play with their friends. Don't let your children win all the time. Remember that they learn some important lessons from disappointment. It will make it easier for children to master the skills they need to recover emotionally and move on.
5. Encourage your children to keep trying, even when they're frustrated. If bad losers don't feel they can be successful at an activity, they nay not do it at all. Letting children know that you'll be proud of them simply for trying will often give them the incentive they need to redouble their efforts. If they persevere, they may find that they can master what they're been avoiding.
6. Use television and newspaper coverage of sports to help children explore their own values. How would they feel if they fell during a skating competition or ski race? Why are the people who have no chance of winning competing? Our children need help interpreting these issues, just as they need adult guidance interpreting the pictures of war that they see in the newspaper or on the evening newscast. If you're watching an event like the Olympics or a marathon race, point out people who are having fun or who are doing better than they had in the past.Encourage children to focus on the changes in their own performance and skills, not on the number of games they win. Focusing on performance and skills is, after all, what professional athletes and other successful people do.