My tips:
1) Learn something from every call. If you don't think you learned something, re-run through the call in your head or talk about it with your partner. Recognize what you did wrong, and recognize what you did right.
2) Realize that one of the most important things an EMT-B can do is provide comfort and a caring hand. If you have an opportunity to help relieve someone's pain (legally

), DO IT!
3) Know the ins and outs of all drugs you can give. What are the indications? Contraindications? What does the drug do in the body?
3a) In addition, realize THAT OXYGEN IS A DRUG. Give it to those who need it, don't give it to those who don't.
4) Don't carry a crap-ton of stuff when you're not on duty. Definitely a cell phone, and MAYBE a CPR mask. Don't carry a pocket ER.
5) Take the job seriously, but have fun. Don't come across as an *** to your patients; why make an enemy when you can make a friend? Joke when the time is right, and don't let the stress get to you.
6) Realize that EMT-B is a very, very basic level. Not saying you haven't learned anything, but advance your learning. Taking college level science courses, like Anatomy and Physiology (I+II), chemistry, psychology, sociology, and other related courses. EMT-B gave you the foundation; start building your knowledge up from there.
7) There are no stupid questions. When in doubt, ASK! Take every opportunity to learn. If you come across something you don't know or haven't heard of, research it!
Hope this helps!
Eric