When cooking fish fillets like salmon, grouper, tuna, halibut, etc. trim the thin part of the belly from the thicker section of the fish and cook them separately to prevent overcooking the thin belly section while potentially undercooking the thicker part of the fillet.
After searing a steak, chop, large piece of fish or even a burger remove the seared meat to a warm section of the grill and allow it to finish with indirect heat. You'll be happy with the moist meat and crispy grilled crust marks if you don't cover it will foil.
To de-bone fish and for more elegant meals - insert the tip of a sharp boning knife into the 'top' of the fish at the head and 'feel' your way to the spine (which should be below the knife blade) and run the knife gently along the spine 'feeling' your way to the tail area. Use two forks to lift off this half then to pinch the top end of the spine and lift it firmly to 'peel' it away from the bottom half of the fish. Replace the top half and serve.
Lay a piece of aluminum foil on top of the fish grilling basket after placing on the cooking grates. This holds heat and captures any moisture, which also helps cook the fish.
I like to brush salmon skin with some teriyaki sauce and flip it a couple of times to make it all crispy. This is tasty stuff and if none of my guests are wise to it, I'll enjoy it myself as I'm finishing the meal for service. When fish is fresh the crispy skin is like potato chips.
When cooking fish, take a look at the size of your grill and the size of your spatula and consider cutting the whole fish into smaller pieces to make it easier to grill and manage on the grill.