Make the captions useful and not merely a copy of some text in the body of the article. Use superscripts and subscripts appropriately. Don't show trivial calculations. There is no need to define what an average is and show us how to calculate it. Graphs should be simple, but complete, with axes labeled, and data points, and fitted functions distinct from one another.
Most journals require a caption.
The editorial guidelines used by the American Physical Society will generally be followed unless you convince me that you should follow the guidelines of another organization. If your career goals and academic path are consistent with your case it will likely be fine with me. See example papers in journals such as Physical Review, or check out their online style guide . The above due dates are subject to change. We ask all physics majors to maintain a portfolio along with their advising folder in the department office.