We Marinate to add flavor to and tenderize meat. Don't waste your money getting store-bought garbage full of soybean oil and preservatives like MSG, autolyzed yeast extract, etc. Making a marinate takes just a minute with minimal ingredients you probably have around anyway. There are no strict ingredients, but basically, all you need is an oil, an acid, and some spices spices.
Oils: Olive, Hemp Seed, Coconut are my favorites.
Acid: Vinegar or Lemon Juice or Alcohol (whiskey, tequila)
Spices: Salt, pepper, basil, cayenne, etc.
Blend 2 parts oil to 1 part acid and whatever spices you desire.
I usually puncture the meat with a fork and pour the marinade over the meat to marinate for at least an hour or more in the fridge.