What are 6 main characteristics of a good watermark?

Your watermark should be legible, unique, non-intrusive, strategically placed, hard to remove, and consistent

Does watermark make my art look professional?

Having consistently high-quality work is what makes you appear professional. If you do have a watermark, consider hiring a designer to help you create it. You can also consult with several designers and ask for their opinion.

Will watermarks protect you from piracy?

If you are really worried about your art being stolen or used without your permission, the only way to ensure it is to never post or upload your images anywhere on the internet.