Soak 8 wooden skewers in water for 30 minutes. Mix cilantro, garlic, margarita mix and tequila (if used). Slide 4 shrimp on skewer and place in pan. Next, pour margarita mix over shrimp skewers and marinate for 30 minutes. Once shrimp has marinated you can cook shrimp on grill, saute pan, or broiler until done. Serve shrimp in salted margarita glass. Last, lightly splach dish with margarita mixer for flavor.