Perhaps, one of the first questions new players frequently ask is 'having the first play, what card should I lead?' Let's start by assuming the other team called trump and you have the first lead. We'll talk about when your team bids further down in this article.
Usually is the best starting lead would be a singleton ace (an ace no other cards in that suit). An ace with one other card in that suit should be your second choice. However, if this ace is in next, or in a suit with three with or more cards, then it would be better to wait. If you were to lead one of these, the bidder would likely trump them. You can make use of these aces later in the hand. When you don't have a boss card to lead, try leading the low card from a King - X combination. Here, your are hoping for the Ace to fall, setting the King up as boss. It is one possible strategy. Even in a junk hand, it's important to try and use every card to your advantage.
If you don't have any of the above, the best lead seems to be the smallest non-trump card from your shortest suit. Based on experience, it's worth a try. No matter what you end up leading, keep in mind you are trying to lead a suit that your opponents will not be able to trump.
Never lead a king from an Ace/King set. This just confuses your partner, who may trump the trick unnecessarily. Also, do not lead the queen from a King/Queen set. Again, this gives your partner the wrong information and they may play an ace where they don't need to.
You should also never lead the suit that was turned-down. The most likely reason it was turned-down was they were void. If you hold an ace in that suit, it is best to wait until later in the hand.
If the dealer picks up and you hold three trump, lead your middle trump, not your smallest. The reason being, you are trying to force out their larger trump. This could leave you in a position to control trump latter on. You don't want them taking the trick with a small trump. Many times this is the only way to set them up for a euchre. There is always the chance that you hold more trump than the maker.
If your partner made trump, and you hold a bower, this should be your first lead. If you hold both, only play the right. Do not play the left, as this may clear out all trump leaving your opponents holding the boss cards. If you do not hold a bower, lead any small trump. Remember, on any call from the third seat, a trump lead, if possible, is mandatory.
Because your partner bid, it is likely that they hold at least one bower. A trump lead will take out a round of trump and should give the lead to your partner. With some of the trump gone, it will increase the chance of your partner's aces taking a trick. You will get a chance to play your aces later in the hand.
By leading an ace or a non-trump card, you are telling your partner that you do not have any trump. Now he knows the other trump could be in the oppositions' hands and he can then play his hand accordingly.
When calling from 1st seat, you should start by planning a strategy.
In doing so, you should ask yourself the following questions:
What suit was turned-down?
Will I be able to control trump?
How strong is my hand?
Should I lead a loser and hope my partner can trump it?
Do I lead a trump, taking some out, to try to make my other cards good?
When do I play my Ace now or wait?
In a hand where you hold aces, a couple of trump plus the right bower. The best lead would normally your right. By removing trump from your opponents' hands, you will increase the chances of making your aces good. When you lead the right, watch to see if your partner follows suit. If they don't, and you hold the left plus another trump, lead the left. The opposition is likely to be holding more than one trump. You don't want them to be able to use their trump against you. If your partner throws off because they can't follow suit pay attention to what card they play. They may be giving you information as to what suit they hold boss cards in.
On a next call, a small trump may be your best lead. There is a good your partner holds a bower. This will draw out a round of trump and should pass the lead to him. This could allow him to play any aces he may hold.