I marinated this salmon with Cousin Leroy's Asian Sauce (hoping to do a review of his products soon), soy sauce, chopped garlic and serrano, and a tiny pinch of rapadura. I generally add all the marinating things on the top of the salmon in a pyrex, then flip the salmon flesh side down to wallow in the yummy flavors for a few hours in the fridge. I always leave the skin on the salmon - it keeps all the moisture in the fish and acts as a natural non stick surface on the grill. I like to marinate salmon with a combo of salty and sweet flavors. Leroy's asian sauce is plum and orange based. Without this sauce you could stick with soy and some brown sugar or rapadura - just a tiny bit of sweet as a little goes a long way.
I place the fish skin side down on a pre oiled grill (just a little of that spray oil will do it) and cook on a medium heat until the salmon is done. I placed sliced sweet onion on the top and drizzled the remaining marinade over that. I like the edges to get charred and smokey looking, the flesh should be fully cooked - almost flaky. It's easier to tell that it's 'not done yet' as the fish will still look raw and firm. Don't OVER cook or it will dry out - and don't squeeze the fish, again that will dry it out. Just let it sit there and do its thing.