Take Interstate 5 South to the Mexican Border crossing (at San Isidro, CA). Once in Tijuana, follow the green sign that reads “Rosarito – Ensenada Toll Road or Scenic Drive”. Drive West towards the ocean (Playas de Tijuana) to first toll booth go south on the coast highway (approximately 25 minutes to the second toll booth), and 20 more minutes to Baja Seasons Beach Resort.
You can also use this link to see a Google Maps image