Locate a partner if possible. While you can use flashcards on your own, having a partner show the cards to you can encourage you to take more time trying to give an answer for each card. When you control the card yourself, you might be tempted to flip the card to the answer quicker.
Time yourself with a kitchen timer or some other device. Since these are music flashcards, you're working on quick recognition. Music flashcards are designed to teach you to sight read music, so the faster you can recognize and name the notes on the cards, the better your sight-reading skills become. Place several cards on the floor or table in front of you, with the questions facing up, and try to answer and turn over as many of the cards as you can in an allotted time.
Play the flashcards on your piano or whatever instrument you use. This can help you not only recognize the note or musical term you're reading, but also allow you to put what you learn immediately into practice. If you have someone helping you, have that person select a note and a musical term, then you play the note to the direction of the musical term. For instance, suppose the combination is a "C" note card with the term "Forte." Since forte indicates that you should play loudly, play the "C" note loudly.