Frothing milk works better using full-fat milk or milk with at least 2% fat content. The more fat in the milk, the thicker and firmer the foam. Avoid skim milk if possible because it’s harder to froth with an immersion blender. You can also use non-dairy milk such as almond, soy, or oat for vegan or lactose-free options. However, note that some non-dairy milk may not froth as well as dairy milk due to its lower protein content.