To boil shrimp, prepare the raw shrimp, and bring the required quantity of water in a pot to boil. Add salt and seasoning to the water, and bring it to a gentle simmer. Introduce the shrimp to the hot water, and cook until they rise to the surface.
To prepare the raw shrimp for boiling, rinse them in cool water, and pinch the heads off, but leave the tails, shells and legs, as they contribute to the flavor. Alternatively, remove the heads, shells, legs and tails, and devein the shrimp by making 1/4-inch deep slits on their backs. Use a knife to slit and remove the veins.
Make a spice bag, using a square piece of cheesecloth, to add flavor to the boiled shrimp. Introduce the spice bag first to the pot, and then add enough water to submerge it. If desired, also add slices of orange, lemon and/or lime.
Heat the water, and when it begins to simmer gently, introduce the shrimp without allowing the water to splash. Cook the shrimp uncovered on medium to high heat for approximately three to five minutes. When the shrimp turn a healthy pink, remove them from the water, and chill immediately to prevent further cooking. Finally, remove the tails, legs, shells and veins before serving.