1. Always discard any items in the freezer that have come into contact with raw meat juices.
2. Do not leave cooked food at room temperature for too long before freezing. Remember, we freeze food because bacteria develops when its left at room temperature.
3. Thawing completely and then refreezing food not only loses taste, texture, and nutrients but could also result in the development of bacteria due to frequent temperature changes.
4. Never taste food to determine whether it is safe to eat. You also should not rely too heavily on appearance to determine whether the food is safe. If in doubt, throw it out.

Also check- How do I manage excess cooked food? Freeze or not? and How best to thaw frozen food?