Avoid text within images, for example a caption or text to identify a part of an image.
Avoid using images as buttons. Using images as buttons requires hard coding the button text.
Understand your images and the meaning they represent. Ensure images are unambiguous. Using thumbs up images to represent "like" may be acceptable in English but offensive in another culture. It is preferable simply to use the word "like" which can then be translated appropriately.
Similarly, take care when choosing emoji's or avoid them.