There isn't all that much to it. If your fish monger has not cleaned it, snip off the fins and, after placing it in a plastic bag, run a knife blade over the body from tail toward head, and watch the scales flake off. The bag catches them nicely. Score the fish just cutting through the skin. As it came to you already gutted, you are ready to go.
Dress the fish by putting some fresh dill (or any other fragrant herb) in the cavity along with some lemon slices. Drizzle some olive oil over the outside, salt and pepper to taste. It's easier if you use a fish basket, as they tend to stick. I just spray it well with food release. It takes about 7 minutes on each side for a one pound fish cooked over a hot grill.
Open the fish basket on a cutting board and lift the fish onto the board. Fillet the fish by making a clean cut behind the head until you hit bone. Then cut down along the fin side just inside the backbone. Swing around in front of the tail and run the knife up along the rib cage back toward the head. Your fillet is now ready to flip off to the cutting board. You may need/want to use a spatula if the fish is very tender and delicate as this one was. Then just gently pull up the bone structure and it will come out in a single piece, leaving you with another fillet. Best to plate skin side down and let the diner eat the very moist, delicious fish off of the skin.
For this fish, I made a Mediterranean sauce, including tomatoes, garlic, Calamata olives, white wine and butter. Leave it to slowly simmer while the fish grills, then top each fillet just before serving. If you've never prepared a whole fresh fish, you will be surprised at how simple it is. More than that, you will be very happy know what a fresh fish tastes like... not fishy... not dry.... just delicious!