Preparing the Shrimp: In a bowl, toss shrimp with olive oil, chili powder, smoked paprika, garlic powder, salt, pepper, and lime juice. Heat a skillet over medium heat. Sauté shrimp 2–3 minutes per side until pink and opaque. Remove from heat.
Assembling the Tostadas: Warm tostada shells slightly in the oven or skillet for extra crispiness. Spread a layer of refried beans on each tostada shell. Top with sautéed shrimp. Add shredded lettuce, diced tomato, shredded cheese, and avocado slices. Garnish with fresh cilantro and a drizzle of sour cream or crema if desired.