honestly nothing you do is going to help you a ton imo... its very different than being in an actual mouth. When I was an assistant i thought i would have a leg up going into dental school because I was doing prophys with indirect vision but doing a prophy or just looking indirectly is way different from drilling with specific dimensions on the order of millimeters indirectly. Everyone struggles at first and within a week or two you get it down no matter how much previous experience you have.
Save your money for your loans or cut your hair in the mirror like mentioned above