* Turning down a bower when having 1 other trump
* Leading trump on defense
* Leading trump on fourth trick
* Leading right bower after calling "next"
* Leading trump against a loner
* Leading right bower against a loner
* Passing with biddable hand
* Failing to call "next"
* Trumping partner's ace
* Not leading "next" through third seat lone call
* Not leading trump to partner's call
* Not leading trump on own call
* Not giving your partner a chance to help
* Double leading trump back to your partner
* Thinking Ace - King suited have the same value (to your partner)
* Forgetting that euchre is a partnership game