For marinades I like to use things that are slightly acidic like citrus juices or small amounts of vinegar...... it helps to tenderize the meat. I like pineapple juice but that's just my own thing.
Other's will argue that a good cut of meat needs nothing others than salt and pepper.
I prefer butcher shops that deal in local meats that are grass fed, chemical free (ideally organic but chem free is fine). really depends on where you are in the city. St Lawrence Market, Kensington, the Healthy Butcher,......there's another one that's escaping me a name that starts with a J,
check out I think it's Ruth Chris' website they have a section on the different cuts and how the prep their meat.