One corner of the mouth is pulled up and back (the only asymmetrical expression). How to Train for Free: A Step-by-Step Guide
: Read free guides like the Medium Beginner’s Guide to Microexpressions to understand which specific muscles (like the corrugator supercilii for anger) are involved. micro+expression+training+tool+free+best
While professional certifications can be expensive, several high-quality allow you to sharpen your skills without spending a dime. Top Free Micro Expression Training Tools & Tests One corner of the mouth is pulled up
You don't need a paid course to reach a high level of proficiency. Use this "Do It Yourself" training plan: micro+expression+training+tool+free+best