Mixing Muffins Use the beaters designed for batter on your mixer. The same ones you use to mix cake batter are fine. Make sure that all your utensils are clean. Sometimes measuring cups and spoons will hold different volumes, it's not right, but it's a fact of life. Follow mixing times and methods of ingredient addition to the letter.
Most failures come from using shortcuts.
Keep the batter as cool as possible. Add frozen blueberries without thawing them. Other frozen fruit should be thawed and chopped into small pieces. Fill muffin cups and bake as soon as possible after mixing. It is very important that the muffin batter is kept cool.