Use measuring cups or measuring spoons! Of course you can always use my method of “Dash, Splash, Sprinkle, or Pour” at will. No measurement just season to taste. And these methods are not done by a professional that will tell you not to try this at home. No disclaimer here you can try that at home! One method I would not suggest cupping your hands or using a straw by holding your thumb on one end. These methods I found are preferred by kids if you let them help. Cupping the hand isn’t bad but the straw takes time.
Back to the serious side, marinating as a general rule use approximately 8 ounces of marinade for every 2 to 3 lbs of meat. You can vary the amount of marinade to preference.