What makes a good form?
A good form is scannable, doesn't require a lot of typing and includes smart labeling and formatting to help users fill out forms correctly the first time.
What are form design principles?
The overarching principle for form design best practices keeps popping up: Make things easy for the user (especially for mobile forms). Limit the amount of typing users need to do to complete a form. One way is to automate as much as possible with features like autofill.