Your going in the right direction! Just go in a local vets office, make sure your cleaned up, not in breeches! And ask for an application and that your wanting to either work or volunteer. Usually they need volunteers and are happy to get them.
You can also go to the high school counciler and ask for volunteer things. I think colleges look at things like that but its good to make up a resume and have all the volunteer jobs on it, becuase even tho its not real work employers like to see the things that you have done in high school, like prep squad...ect.
When your just starting out and looking for work. Then you can start to replace the volunteer work with real jobs, its better to have a full resume with volunteer then an empty one!
From east to west a travlin gypsy found her prancing pony for now their hearts run as one...into the north