How should you generally identify your station when attempting to contact a DX station during a contest or in a pileup?

In a pileup or contest, time and efficiency are critical on the airwaves. Sending your full call sign once or twice provides the DX station with exactly what they need to log you without clogging up the frequency with unnecessary information. Sending only the last two letters (often called "tail-ending" or partial calls) actually slows down the process, as the DX station will have to ask for the rest of your call sign, wasting valuable time. Similarly, sending grid squares or lengthy sequences like repeating both call signs three times takes up too much time and creates unnecessary interference for others. Keep it simple and concise: state your full call sign clearly, and wait for the DX station to acknowledge you.