Headings should be an outline of your content. They should allow web visitors to easily jump through your content to get to the section of content that they are interesting in reading. Headings should make sense out of context of the page.
Headings can be read by screen readers as a way for someone to navigate through your webpage quickly. Headings are also great for SEO.
Content placed in a heading tag will help your webpage to get more search ranking for those terms. It is important to be thoughtful when using headings and not abuse the ability to gain search ranking. The latter will result in a less accessible webpage.
It is advisable to use headings in order and not to jump heading levels just to achieve a specific aesthetic provided by the heading.
Headings should range from h1 to h6. Headings should only be a few words long.
Empty headings can result in the section of content inadvertently being skipped over by screen readers. It is important to remove extraneous heading tags from webpage content.