I have a foolproof marinade, its called empty everything in the fridge into a plastic bag and throw some meat in it.
But mainly I stick with soy sauce, sweet thai chili sauce, some ketchup or tomato paste, some dried garlic and some water to dilute any saltiness. I try to avoid using too much salt if I make steak because I use meat tenderiser which is very salty.
Happy BBQ'ing!