Use a paddle attachment

Some recipes might specify using a whisk attachment, but according to Mom's Baking Co., the paddle is preferable for almost all types of buttercream for a number of reasons. First, regardless of what you are making, the paddle works best for creaming butter and sugar. When comparing a whisk to a paddle, the whisk will always include more air to the food you're mixing. It performs a great job of making the butter velvety smooth. The frosting should contain some air, but a whisk can easily incorporate too much air too quickly.

Not to mention that while handling icing, paddles are simpler to use. Such thick substances frequently become stuck in the whisk's center. You can easily scrape the icing off with the help of the paddle. The best way to get comfortable using your paddle when creating buttercream is to use this traditional vanilla cake recipe (and using a whisk will soon be a thing of the past for you).