All text should be legible from 5 feet away. Super and subscripts can be 18 point. Avoid excessive use of all-caps lettering. Photos should be clear and depict the intended object or thought. If they don t, consider artwork instead.
Photos are indeed worth a thousand words and can enhance text.
Make overall presentation pleasing to the eye. However, artistry does not substitute for content. Simplicity and legibility are more important than artistic embellishments. Photo backgrounds can be either attractive or distracting, so consider your choice carefully. Setting apart your text in boxes is a helpful communication approach.