Baking powder loses strength with age, so fresh is best. Always use fresh baking soda or make sure that it has been stored properly. Baking soda absorbs odors and loses strength with age. Fresh is best. Fresh milk and powdered milk is fine to use in all types of muffins.
Milk makes muffins taste richer and brown better.
Butter, margarine and salad oil also work well. Muffins lend themselves to many spices. You can be creative when using spices to flavor muffins. Add zest to a dry pre-mix muffin with the kind of spice you like. Cinnamon and a little ground clove will enhance the flavor of almost any muffin.