How to make thin hair thicker?

I'm curious, could you please explain how one can go about making their thin hair appear thicker? Are there specific hair care routines, diets, or products that have been proven to be effective in achieving this goal? Are there any common misconceptions or mistakes to avoid when trying to improve the appearance of thin hair? I'm particularly interested in natural and non-invasive methods, but I'm open to considering all options. Thank you for your insights!