What's really important is SOURCING: all meat should be either grassfed, pastured or wild. Avoid farmed fish and grain fed livestock.
That's about it. If the meat is good, it's safe to eat as it is.
Of course, you can still marinate it to make it more palatable, but most users here stop doing so at a certain point.
I find lemon juice goes well with beef, and ACV with fish.