All three trump two suited hands should start by using the principles already laid out. There will be times when you have to adjust how you play the last couple of tricks by looking at the cards left in your and use the information gathered from the first tricks.
In this hand you are the dealer and sit in South position. This seems to be a fairly safe call so you pick up the nine of spades. The king of clubs has no value and is discarded.
East seat starts by leading the ace of hearts. North follows suit with the jack and West also follows suit by playing the 10. Being that you are void in hearts, you trump in with the 9. This is your first trick with one trump played.
Now you(S) lead back the queen of spades. Because you hold an off-suit ace you're trying to rid the opposition of their trump. This should help in making that off-suit ace good. East play the right, taking the trick. North plays the left and West follows suit with the ten. Each team has a trick apiece. Five trump are now out of play. There is one left in your hand - that leaves one possible trump, the ace, in the wild.
East leads back the 9 of hearts. Your partner(N) plays the queen, and West plays the king. You trump in and take the trick with your king. This is your second trick.
Now to make one last trick for the point. You know that there may be one trump left against you. It would be a good guess that your partner doesn't have it or he would have played it instead of the left. You are hoping that either the ace of trump is buried or, if it's out there, then the holder also has a diamond.
To give your team the best chance of success you lead the king of diamonds. Why? Because there is a chance first seat will duck and let the trick go by, hoping their partner has the ace. (Remember: at this point they need the next two tricks for a euchre.)
As it turns out the trump ace is buried and your king walks, giving you the point. A little bit of luck, sure, but winning means taking chances. Good luck just makes it easier.