Add Custom Form Properties to the Template
When you create a new/custom field on a form, this field is created on each contact's profile. If over the course of time you create several forms and forget what you called "mailing address" on a past form and create "customer mailing address" on this new one, you will have two fields that have the same purpose. This makes it extremely difficult to pull lists going forward.
I propose you populate the form template with not only "standard fields," but also those that we have already created so that room for error and duplicate fields diminishes.