Have the Necessary Tools
Just like with facial makeup, it's important to have the right tools to properly apply body makeup to your legs. While you might be tempted to use your fingers, don't. Your fingers will add oils and change the consistency of the makeup, making it harder to blend in.
Instead, use a latex sponge to blend the makeup into your skin and create the most natural shade with your skin tone. A set of good brushes can also help you cover up blemishes with concealer. And have a variety of sizes. Smaller brushes should be used for small blemishes to make sure the concealer goes only where it's needed. However, a bigger brush will help when covering up a larger scar. Finally, you'll need a powder puff at the end of the process to finish your work with a translucent powder.
Don't forget to properly wash your tools after each makeup application to prevent the build-up of bacteria, which could cause acne.