There isn’t one universal style—the best profile or cover image depends on the person’s goal and audience. A photo meant to look professional may be very different from one meant to feel social or playful.

That said, a few portrait basics help in most cases:

• Make the subject easy to identify, especially in small profile-image sizes. Usually this means the face should occupy a meaningful part of the frame.
• Separate the person from the background, either with shallow depth of field or a simple/plain background.
• Use flattering light. Avoid harsh shadows or accidental backlighting unless it’s intentional; soft side lighting often works well.
• Aim for expression. A natural smile or clear facial expression is usually more engaging than a stiff passport-style pose.

For professional use, a simple headshot-style image with clean background and appropriate clothing is often strongest. For personal/social use, a wider or more environmental image may better communicate personality and context.

So the main “rule” is to match composition, expression, background, and styling to the platform and the impression the subject wants to create.