Preheat oven to 180°C (350°F)
For each muffin variety, mix dry ingredients (flour, sugar/brown sugar, baking powder, baking soda if needed, salt)
In another bowl, mix wet ingredients (milk, oil/butter, vanilla, and any flavor-specific ingredients)
Combine wet and dry ingredients until just mixed
Fold in mix-ins (blueberries, chocolate chips, poppy seeds, carrots, walnuts, etc.)
Pour batter into muffin tin
Bake at 180°C (350°F) for 18-25 minutes depending on variety until golden brown
