When you make the trump next in suit, always lead a trump, unless you hold the tenace of Right Bower and ace, and even then it would be good policy to lead the bower, if you hold strong plain-suit cards.
When you hold two trumps, two plain cards of the same suit, and a single plain card of another suit, lead one of the two plain cards, for you may win a trick by trumping the suit of which you hold none, and then, by leading your second plain card, you may force your opponents to trump, and thus weaken them. With such a hand it would not be good play to lead the single plain card, for you might have the good fortune to throw it away on your partner's trick, and ruff the same suit when led by your opponents.
When your partner has made or adopted the trump, it is bad play to win the lead, unless you possess a hand sufficiently strong to play for a march. If your partner assist you, and has played a trump, and you have won a trick and the lead, do not lead him a trump unless you hold commanding cards, and are pretty certain of making the odd trick or a march, for your partner may have assisted on two trumps only, in which case such lead would draw his remaining trump, and, in all probability, prove fatal to his plans.
Having lost the first two tricks and secured the third, if you hold a trump and a plain card, play the former, for, in this position of the game, it is your only chance to make or save a euchre.
There are only two exceptions to this rule, viz. when you have assisted your partner, or when he has adopted the trump and still retains the trump
card in his hand. In the former instance you should lead the plain card, trusting to your partner to trump it; in the latter case you should also lead the plain card, unless your trump is superior to your partner's, and your plain card is an ace or a king, in which case you should play a trump, and trust to the plain card to win the fifth trick.
The reason for this play is manifest. If your opponents hold a better trump than you do, it is impossible to prevent their winning the odd trick, and, therefore, the euchre or point; but if they hold a smaller trump, your lead exhausts it, and you may win the last trick with your plain card.
This position frequently occurs in the game, and we recommend it to the attention of the novice.
Concluding Hints.
Never lose sight of the state of the game. When the score is four all, adopt or make a trump upon a weak hand.