Whether you have completed your degree or not, look into local colleges for art courses. If you already have a degree, you may be able to audit classes from your old university or college, so you can take the course and pay a small fee for instruction and practice. Or, community colleges may offer classes at a small fee for artists. You can usually find classes on the nights and weekends so you don't have to worry about teaching around your art classes.
Check to see if your local town or city has a community center that offers enrichment courses. These courses are for adults who would like to enrich themselves in a particular area, and usually include art courses. Most of the time, these community classes take place in the summer, or during your vacations, but you can find night and weekend classes as well
Pay attention to local museums and art centers, as well as local universities. These organizations often put on master classes, where they invite a famous or well known artist to come to your city or town and put on a master class. Typically, these will cost a fee and will sometimes require you to take a personal or vacation day from work to attend. However, you'll learn much more at these types of classes than in a general art class.
You don't have to go anywhere to find art courses other than your school district or school. You may be surprised at what you can learn from other art teachers. Ask if you can sit in on the art teacher's class from the grade above you, or even from a younger grade. Even if the teacher is teaching something you already know how to do, which is probably likely, you can learn a lot about techniques and teaching styles by sitting in on some classes.