I'm all about the marinades. My advice - buy lots of different spices, herbs and whatnot - Cayenne pepper, paprika, garlic granules, ginger, basil, oregano, chilli powder, the **** lot.
For example, tonight I cooked up a couple of rainbow trout fillets with rice. Marinade I made up was cayenne pepper, garlic granules, ginger, smoked paprika, mixed herbs, soy sauce and a touch of water so that you can mix it all up into a paste. Make the paste in a bowl so that you can chuck the fillets in there and cover them, leaving them for a while. Heat up a non-stick frying pan with a bit of olive oil, wait till its pretty damn hot and put the fillets in skin side down and keep them there for a 3-4 minutes then flip them over and cook for 2-3 minutes - to taste really, I cook them longer as I like the skin crispy. Pretty simple and quick but damn tasty!