I wrote my own. Ask these questions (the important ones and any more you want added).
Do you have a medical condition/medication that causes hair loss?
Have you ever suffered with alopecia?
Do you have psoriasis on your head?
Do you have eczema on your head?
Are you allergic to metal?
Are you allergic to acetone/alcohol?
Do you have a sensitive scalp?
Now here is your disclaimer part:
A non-refundable deposit of......has been paid in full.
I understand that (your company) will act in my best interests, I understand that my hair may need to be cut and blended to suit the style of extensions. If I am simply not happy with the service, I understand I cannot get a refund and must pay for the removal of the service. I agree to adhere to the aftercare guide issued by my technician, and failure to do so will result in problems. I understand the risks and challenges I may face going forward and my technician has addressed these with me. I understand for the continuation of my service and hair safety, I must have monthly maintenance appointments and my extensions must be removed professionally.
I hope this helps.