Reading lips is assumed to be a skill that’s easy to acquire. The go-to strategy for hearing people when talking to Deaf and hard of hearing people is to speak louder and to over-enunciate. This can be a mixed bag, as really the only helpful part would be the natural slowing down of speech.
Speech is a rapid, fine motor movement, as this video demonstrates beautifully:
As with so many things, listening to the people who experience this day in and day out is the best way to gain insight and understanding.
h/t Swiss Miss