For tenderizing, if papaya juice is available there is nothing natural that is better. Add it to any marinade for a nice sweet tropical flourish and to tenderize tough cuts. Pineapple juice can substituted, but papaya is king in my book.
My go to marinade is equal parts soy sauce, worcestershire sauce, and oil. Add in black pepper, onion powder, and garlic powder.
For a citrusy one, add in a container of frozen OJ concentrate and minced fresh ginger.
Add fresh herbs if they're handy such as rosemary, thyme, and chives.