1) Take as many rigorous math and science classes as you can. This may be tricky if your school is small because you might not have access to honors level or AP science courses. If you are able to take dual enrollment classes, you might consider taking statistics, calculus, and/or some of the introductory science classes that aren't taught at your school. This is less about "getting ahead to save money" and more about making sure you have a strong foundation for your science classes when you begin college. Many college freshmen struggle to adjust to college science classes. Vet schools know that happens to a lot of folks, but if you can begin to learn how to be a good student in high school, you'll probably find the transition to college less bumpy.
2) Look for opportunities to get experience with a lot of different types of animals and with vets working in different types of settings. Vet schools like to know that you've spent time observing and handling household pets, large farm animals, and maybe some exotic species or wildlife and that you've seen more than just a traditional vet clinic setting. You can look for opportunities to volunteer at shelters and wildlife rehab centers, join 4H and learn about raising farm animals, or try to get a job helping a local vet. Reach out to local vets to see if you can shadow them; if you have different types of practices nearby (clinic, shelter, emergency center) try to get shadowing in each of those settings. If you start now and continue through college, you should have a lot of great experiences with different species in different settings, which will allow you to share with vet schools the type of vet you'd like to be and the impact you'd like to make within the profession.
3) Look for opportunities to interact with people from various backgrounds and to develop leadership skills. As a vet, your patient will not be able to speak with so you will rely on communication with human owners. The more skilled you become interacting with others, the more effective you'll be as a vet. Get engaged in a club, sport, or activity so you can develop teamwork skills while also making a positive impact on your community.
Mary Jane recommends the following next steps: