September 9, 2019 Form
Make structure clear, and provide navigation to reinforce it. Your form will be divisible into sections so think about the broad groups of questions being asked. Whatever your groups of questions are, make sure they follow the right order and give the groups clear section names.
Provide examples of the sorts of answers you are looking for, and where appropriate, provide guidance notes as near as possible to the question they relate to (i.e. in the actual form).
Pre-fill where at all possible. If a person has already filled in a form for your organisation they will be frustrated if they have to fill in the same information again. It is difficult for organisations to get their systems to pre-fill known information but when pre-filling is achieved, customers really feel valued.
Provide checklists. As users complete your form, you may well be asking them to provide supporting information or attach supplementary documents where required. Providing a checklist, often at the beginning or end of a form, helps remind users about all the things they should remember to attach, and any further steps they need to go through.
Also make sure that you make good use of features like running headers and footers on every page to remind people what the form is, where they are, and what page number they are on.
In paper forms the specific sub-questions cannot be hidden from the user when they are not relevant to them - but in interactive forms this is relatively easy to do. Use progressive revealing as much as possible in your form design to shield your users from questions they do not need to see.