theres no need to fear cook is here!!!!
as far as steak goes you should be eating top round or other very lean cuts. stick to dry rubs especially if your going to grill the steak. Dry rubs will give a better flavor on open fire then marinades will. If you are in need of some good rubs this is where I purchase all of mine they are a little pricey but worth every penny.
PENZEYS Spices Home Page just because you are eating healthy doesnt mean you have to compromise flavor.
But if you are set on using italian dressing buy the powdered mix where you had your own oil. use extra virgin olive oil and use LESS then the it says on the pouch and add water in its place. that way it dissolves the flavoring all the way. You can also add basalmic and some fresh garlic and make a vinnigerette to marinade it in.