You'll need to be a little more specific.
But if we're just speaking in generalities:
1. Take your job seriously, even if you don't think others do. You're a teacher, so act like it both in the classroom and out.
2. Remember why you came here. If it was to gain teaching experience, then gain teaching experience. If it was to learn Korean, then learn Korean. If it was to earn money, then earn money. Don't get distracted.
3. Maintain both respect and curiosity for Korea.
4. Know that you don't know. One of the worst habits you can pick up is acting like a know-it-all. Whether you've been here for a day, a year, or a decade, you'll always learn new things provided you let yourself. I haven't decide what is more annoying: unsolicited advice from "veterans," or know-it-all newbies who don't listen.
5. Google is your friend. There's a ton of information about Korea and Mokpo available on the internet.
6. Take your job seriously, even if you don't think others do. You're a teacher, so act like it both in the classroom and out. Yes, it's worth repeating.
Again, if you're more specific I'm sure you'll get some different answers. Maybe you could share a little about yourself.