This is really hard to do. You will forget to eat lunch because you are redoing something for your afternoon classes, following up on emails, frantically making copies, or a whole host of other things, but it's healthy to leave your room every now and then. It's nice to chat with an adult or bounce ideas off of another person, so give yourself permission to leave your room during lunch or plan periods, even if it's only for ten minutes. Eat in the lounge once a week or ask a co-worker if you can join her for lunch in her room. Build relationships with staff the same way you do with your students. Just make sure you stay out of the drama. Every building has it. Don't engage. You have way more important things to do...like learning your curriculum and becoming a great teacher!
Another tip for getting out of your room is to go observe other teachers. Your very best resources are other great teachers! It will become obvious to you who the best teachers are; your students will talk about them all the time. Go see those people. Listen to how your colleague reacts to a smart-aleck kid who gives you trouble, notice how another teacher transitions from one activity to the next, reflect on how someone set up his/her room and why. It doesn't matter what grade or subject they teach because you are observing the person and his/her craft. However, if you are struggling with a particular topic in your class, it can be tremendously valuable to observe someone in your own content area as well.
These are the people that truly run your school. Go out of your way to greet them each day, treat them with respect, and develop a positive relationship. Be sure to chip in for holiday gifts or Administrative Assistant Day. You will rely on them more than you realize, so it is really important that you get along!
If your school has an active social committee, they may occasionally plan events for the staff. Go to them. You don't have to go to everything, but pick things that fit into your life and make the time. For example, my school has a Friday morning breakfast club. We take turns bringing in food and people really look forward to it as a way to connect with each other, if only for a few minutes before class. Maybe your school has a holiday party, a welcome-back picnic, or an end-of-the-year shindig. Go! Learn about your co-workers as people with lives outside the building and develop those relationships. It will make the working environment so much more enjoyable and rich. Just one word of caution here: as the new kid, stay away from the cocktails at these after-school events, or at least slowly nurse something for the evening. The last thing you want is to do or say something you wouldn't have under other circumstances.
Let's face it: every school environment has its typical cast of characters that mimics the students you teach. There is the class clown who is usually in charge of the social committee, the mean girl who is always looking for a new piece of gossip, the over-achievers who are on every committee, the burn-out who is counting down the days until retirement, and the veteran with strong opinions. As the new kid on the block, you have to learn how to navigate all of these personalities without alienating yourself from the start. So the best advice I can give here is to watch, listen, and observe during meetings. Let the others do the talking and wait until you are brought into the conversation. Earn their respect without being a know-it-all.
New teachers have a tendency to say "yes" to everything, and people may try to take advantage of this. Your primary goal for your first two years teaching is to hone your craft, which takes time - your most precious commodity. My first year teaching I signed up for lunch duty and after school supervision because a) it paid extra and b) I thought it would be a great way to get to know the kids better. While this was true, it also contributed to my late nights at school. Instead of using those times to research and write lesson plans, grade papers, make copies, return phone calls and emails or meet with students, I was doing other things. It's OK to turn-down things that will take away from your most important job: becoming a great teacher. The committees will still be there when you're ready for them.