WHISK olive oil, vinegar, garlic, Italian seasoning, salt and pepper until blended. Combine marinade with 1 to 1 1/2 pounds meat, chicken or seafood in 1-gallon resealable plastic bag.
MARINATE in refrigerator, turning several times: meat, 1 hour; chicken or seafood, 30 minutes. Remove meat, chicken or seafood from marinade. Discard marinade. Grill or cook as desired.