Personally, I wouldn’t poke my meat with a fork while marinading.
A good marinade usually starts with three basic ingredients: an oil, an acid, and herbs and spices. The oil helps helps transport the flavor of the spices and herbs, as well as helping in forming a good crust while grilling. The acid tenderizes the meat, and the herbs impart the flavor.
For oils, you can use vegetable oil, olive oil, light sesame oil, pretty much anything.
For acids, lemon juice, lime juice, wine, orange juice, mustard, soy sauce, yogurt, etc…
For herbs, garlic, rosemary, pepper, thyme, etc.
Probably the simplest marinade out there is Italian dressing. You’ve got all your basic ingredients in there: oil, acid, herbs. Pour it over your chicken, put it in a ziploc bag, and let it sit for an hour in the fridge.
What you will need to know is that different meats require different marinading times and different approaches. Fish and boneless chicken only require an hour to marinade. Beef and pork, 4-8 or more hours. Fish and chicken also don’t require as much acidity in the marinade…you run the risk of overtenderizing your meats.
You don’t need to cover your food with the marinade. A half-cup or so will do for a two-pound piece of meat. Just turn the meat from time to time to ensure even distribution.
To give you an idea of what I might do for a beef marinade, I would take a half cup of oil, a half cup of a hearty red wine, a clove or two of garlic, some rosemary sprigs, and pepper and marinade the meat in that.
For chicken, I like an African/Portuguese piri-piri marinade. One part oil, one part lemon or lime juice, and lots of hot red chiles (Thai birds’ eye).
Also worth noting is marinading is best reserved for tougher and cheaper cuts of meat. You don’t have to marinade the heck out of everything. Sometimes, you just want the pure flavor of the meat to come through, like in a nice filet or T-bone. People can get too carried away with their marinades, sometimes.
Have fun and experiment. Part of the fun of marinades is developing your own.