Sign up for a Delta SkyMiles account (see Resources).
Book flights through the Delta website. Make sure to use your SkyMiles account number each time you book a flight so that the miles will be credited to your SkyMiles account. Visit the MQM Calculation website (see References) to figure out whether your flight qualifies.
Sign up for the "SkyMiles Insider" newsletter (see Resources) to receive additional specials and bonuses that generate MQM miles to help you reach the 25,000-mile mark.