MARINADES: There is a variety on the market today. Stubb's is one of many quality choices available. Read the ingredients of whatever you choose, watching for lots of hidden sugar which reduces the healthy aspects. Marinades are effective because the ingredients within them help to break down the meat tissue making it softer as well and juicier.
If off-the-shelf preparations don't flip your switch, try soaking meats in a baking pan filled with inexpensive Italian dressing. Use the cheap store brand as all types work equally well for this application. Place it in the fridge overnight and the difference will amaze you!
SEASONINGS: These can also be a great weapon in the battle of the bland. Too much salt is not advised -- so try to use non-salt spices more than not. Soy sauce makes a fine "potion," but use the low-salt variety. It's generally better if you mix soy sauce with a few other spices too or it may overpower the meat.