After you win, thank the other team for showing up. Without them, you just had practice.

Winning requires an opponent willing to turn up, travel, warm up and lose in front of people. Without them the afternoon would have been a drill with nobody keeping score, and that is the part that disappears in the celebrating. Thanking them is not really politeness. It is an accurate description of what just happened.

Go down the line properly instead of at speed, and say one specific thing to whoever gave you the most trouble. If you organised the game, thank whoever travelled for it. The habit makes losing easier later, since you will have practised the conversation from the easy side first.