In a large mixing bowl, combine olive oil, lemon juice, salt, pepper, oregano, paprika, and garlic powder. Whisk the mixture until it's well-blended and smooth.
Gently fold in the shrimp, ensuring each piece is evenly coated with the marinade. Allow the shrimp to marinate for a minimum of 15 minutes, with an option to extend up to 2 hours for a more intense flavor.
Thread 4-6 shrimp onto each pre-soaked skewer, arranging them on a plate as you prepare the remaining shrimp.
Preheat a grill or grill pan over medium-high heat. Grill the shrimp skewers for 2-3 minutes per side, or until the shrimp turn pink and become opaque.
Serve the shrimp hot, garnished with freshly chopped parsley and lemon slices for an extra burst of flavor, if desired.