You are the visual translation of information. What good is all the information in the world if we can’t easily understand it? You hold the keys to hierarchy and contrast and layout, the keys to visual communication.
Don't use placeholder text.
Don't use disabled form fields and buttons, whenever possible.
Don't make multi-column forms.
Do make sure labels and instructions are always visible.
Do put your labels and instructions above text fields.
Do make sure your labels, inputs, and any help text are associated properly.
Do make sure all text meets WCAG colour contrast requirements.