Make each field self-explanatory
Put a visible label next to every input and use examples only when they clarify the expected format. A placeholder should not be the only label because it disappears when someone starts typing.
Group related questions and keep the sequence close to the way a person thinks through the task. On mobile, use input types that bring up the right keyboard.
Validate at the right moment
Do not interrupt someone for an error while they are still entering a value. Validate after a field is completed or after submission, then show a concise explanation beside the field.
Preserve values when a submission fails. Move focus to a useful summary or the first invalid field so keyboard and screen-reader users can recover quickly.
Confirm what happened
After a successful submission, show a clear confirmation and explain what comes next. If the service sends a follow-up email, say when the person should expect it.
Test the form with keyboard navigation, autofill, narrow screens, and deliberately incorrect values before launch.