Are there any general rules in marinating beef?

You want to use more vinegar than oil and most any seasoning will work. I like to use red wine or a good balsamic vinegar and garlic for a basic marinade. i would marinate the meat for up to 24 hours but remember that if you over cook the beef then it will get tough. rare or medium rare is best for a steak and a long slow cooking process with low heat for a roast is best.