Whether or not you should smile in a headshot depends on the context and intended use of the photo. Here are some considerations:

1. Professionalism: If the headshot is for a professional purpose, such as a job application or a corporate profile, a natural, friendly smile is often appropriate. A smile can help create a welcoming and approachable image, which can be important in professional settings.
2. Branding: If the headshot is for personal branding or marketing purposes, a smile can help communicate your personality and values, and create a connection with your audience.
3. Industry standards: Different industries may have different standards for headshots. For example, headshots for actors may have a more dramatic or serious look, while headshots for business professionals may have a more approachable and friendly look.
4. Context: The context of the headshot can also influence whether or not to smile. For example, a headshot for a LinkedIn profile may require a more professional look than a headshot for a personal website or social media.

Ultimately, the goal of a headshot is to create an image that represents you in the best possible light and helps you achieve your goals, whether that's landing a job, promoting your brand, or showcasing your talent. A friendly smile can be a powerful tool in achieving those goals, but it's important to consider the context and intended use of the photo to determine if a smile is appropriate.