Tips for Creating Accessible Text, Headings and Documentation
Avoid writing in all capitals. This slows down reading speed and makes it difficult for some users to read your text. You may be trying to emphasize something using all-caps, but the end result is making that item harder to read.
All headings should be used hierarchically. They should not be used to obtain a certain visual style.
Headings should only go down one level, or back up to a previous, higher level.