Put the label above the form field, not beside it.
Consider font size, recommended 16px especially for form inputs.
Labels & Inputs need to meet color contrast. See Contrast.
If a form field is required, at the beginning provide textual indication and description of associated symbolism, e.g., "* denotes required field."
Form boundaries must comply with color contrast. See Contrast.
If there is an error, the error message should appear beneath the field in error, available using both color and text.
Utilize real-time validation to prevent users from submitting to only find the data input was invalid. This reduces anxiety among those with cognitive, anxiety or short-term disabilities.
Provide Descriptive Error messages. For example if a password requires symbols, numbers, or capitalization, indicate that in the error message. “The password must have at least 6 characters and 1 symbol.”
for dates, if user enters a date that occurs in the past, be descriptive of their error, e.g., “Date occurs in the past.”
Consider use of “input masks” which help users focus on task at hand and follow along the information that they need to provide and reduces incidence of error.