Include a clause that states that your manager needs to check your availability before booking modeling jobs. Add a clause that states you are not an employee of the manager but a client paying the manager to do a service for you. State the percentage you will pay from each of your bookings to your manager.
A jammed finger can lead to some complications, including: long-term pain and swelling in the joint, known as traumatic arthritis; stiffness in the finger; weakness in the finger; permanent inability to straighten the finger; deformity of the joint
Any finger injury is eventually going to need splinting. You can tape a metal strip or a stick to the bones adjacent to the sprained finger joint. Popsicle sticks are popular for this. Many times you can just tape the jammed finger to an uninjured one. We call that a buddy splint. You can tell if it feels stable enough with this.