• Shortening - Shortening is easy to spread with a pastry brush or paper towel and it ensures the same even coat you get with butter. Unlike butter, you will not affect the muffin's flavor.
• Liners - Paper and aluminum liners are a popular option for muffins and cupcakes. They make handling the finished baked goods more sanitary and are often preferred if you're taking them to bake sales or some other communal gathering. Some bakers prefer to spray the liners with cooking spray as well. Other bakers don't like the finished effect liners have on their baked goods.
• Parchment Paper - An alternative to liners, cut 5-inch pieces of parchment paper and push one into each cup of your pan. The excess paper makes removal easy after baking because it can simply be lifted out. This may not give you the perfectly round shape of the tin, but it does have a nice look that can actually dress up the average muffin.

Professional Baking Grease - Available at cake supply and many online stores, you can always turn to pro baking grease for your muffin tins. It's also very easy to make yourself: mix equal parts shortening, flour, and oil until light and fluffy.