A traditional print form that is intended to be filled out by hand is inherently inaccessible to people who can't see it and to people who don't have sufficient manual dexterity to fill in the form fields with pen or pencil.
As you gather this information and provide them with valuable content that helps solve their needs (or even open their eyes to a need they didn't know they had), you can start asking for more information from them. Consider making some fields required; usually these fields are identifying information and information you need to categorize your leads. Other fields make optional; these fields are the nice-to-haves but aren't required to help you segment. In conjunction with smart fields and progressive profiling, your ability to remove fields of known data and replace it with new data makes form submissions easier for your existing contacts.