2-Hour Rule
Discard all perishable foods such as meat, poultry, eggs, and casseroles, left at room temperature longer than 2 hours; 1 hour in temperatures above 90 °F.
Keep HOT Food HOT
If you plan to eat at a later time, take-out or delivered food should be divided into smaller portions or pieces, placed in shallow containers, and refrigerated.
Keep COLD Food COLD
Refrigerate perishable foods as soon as possible, always within 2 hours after purchase or delivery.
Leftovers
Refrigerate or freeze leftovers in shallow containers. Wrap or cover the food.
Reheating
Reheat sauces, soups, and gravies to a boil. When reheating food in the microwave oven, cover and rotate food for even heating. Always allow standing time before checking the internal temperature of the food.
More info: http://www.fsis.usda.gov/FactSheets/Safe_Handling_Take-Out_Foods/index.asp