What I enjoy most about visiting schools is the practicality of everything. We get the chance to see real school librarians in their natural environment. There were several things that struck me as important, a list follows:
Don't weed in your first year, in fact, don't make any drastic changes in your first year. I think this is true in any job. You can't come into a new place and immediately understand the culture of the environment. If you try to make changes without having the support of those around you, you risk alienating the other employees. So, take a year. Be patient. See how things run, how people interact, and what kind of resources you have access to. By taking the time to build these relationships, you can make changes much easier in the long run.
Get involved as much as you can. I was a bit overwhelmed by the amount of involvement of the School Librarian, but by not saying no (to almost anything), she has made herself indispensable to those in need. Again, it's about building those relationships.
Once that first year is over, don't be afraid to change things, try new tactics, and make the library your own. Again, this is true in any job, but a bit easier to do when you have your own space to grow into. Take the posters down, move the tables around, wander through your collection (I once heard a school librarian say that she spent at least an hour a week shelving, so she could keep up with the collection and what was circulating), reach out to those who don't naturally come to the library (English classes are always in the library, math classes, maybe not so much), etc.
Finally, keep reading and learning about school libraries. When the new principle came and asked about implementing accelerated reader in the school, the school librarian put together recent articles about why programs such as that wouldn't necessarily be the best idea (or achieve the goals they were working towards). She could only do this because she had continued her education.
Overall, it can seem pretty overwhelming, what with budget cuts, employee cutbacks, decreased funding, the cyclical cycle of enrollment, and overall fluctuation in the education system. I constantly worry that I won't be able to keep up with everything, but I can only do the best that I can do.