Never add salt to food that you are going to freeze, because coldness intensifies flavours. Add seasonings and salt when you use the food that is in your freezer.
Meats and fish thaw faster if you immerse them in a container with water and a little vinegar.
Ice for cocktails:
If you are making ice to be served with cocktails, put a cherry or an olive in the ice tray and your ice cubes will look very nice.
Ice in a hurry:
If you need your ice in a hurry and can not find ice anywhere, put an already frozen ice cube in the tray and the other one will be ready faster.
I know that it seems weird, but if you boil the water that you are going to freeze, your ice will be ready faster. Boiled water has less oxygen and it will freeze faster. It will also look clearer.