It is important to buy fresh fish from a reputable supermarket or specialty fish market. That said, fresh fish does not smell "fishy". Simple as that. My favorite kinds of fish to bake are halibut, haddock, sole and salmon (sockeye, preferred).
Prep: Purchase your fresh fish and unwrapp keeping on ice in a dish in the refrigerator until ready to cook. At cooking time, preheat your oven to 400 degrees F. with rack in the middle of the oven. In a baking dish, spray with a cooking oil and then put the washed/dried piece of fish into the baking dish. Have some olive oil, butter and optional Panko Bread Crumbs to put on top of your fish. Seasonings: Kosher salt, crushed pepper, parsley or dill. Be sure to have an oven mitt ready as well as a large spatula for serving.
Baking: Fish cooks quickly at high heat. Therefore, allow at least 15 minutes until fish looks firm and flakey. Do not over cook the fish. You might see some whitish protein form on/around the cooking fish. This means it is just about cooked. A firmer fish like halibut will turn a nice white color and brown a bit on top.
Serving: Serve right from your baking dish onto a plate. Think about preparing some fresh, steamed veggies as a sidedish and/or a carb of your choice. Please check out my recipes for Couscous and Quinoa. A baked potato works well, also. This is a very healthy meal.