Ask for contact information: name, address, phone number and email. Include this at the top of the form.
Ask for the date of birth. If the actors are minors, you'll need permission from a parent of guardian to have the actor work with you. If you are auditioning specifically for a child's role, include a space on your form for the contact information of a parent or guardian.
Ask for emergency contact information. Have them list any medical conditions they might have, or any other conditions that might impact the production. For example, if the set has a lot of high walkways and an actor is scared of heights, you could have a problem.
Ask for schedule conflicts. If you are doing an amateur or a school production, you are going to have to work around a lot of work schedules. If an actor has too many conflicts, you may not be able to use him no matter how good he is.
Ask for previous performances. Professional actors will provide a headshot and resume, but students and amateur actors may not have one yet. Provide space to list their most recent and most relevant productions.
Ask for physical attributes, such as height, weight, eye color and hair color. Many of these will be listed on an headshot or resume, but it can be helpful to keep them on the form. Even then, most headshots are black and white, so directors will want to refer to things like hair color.