1. Local colleges for design classes.
2. Some local colleges have landscaping classes that include "hands-on" irrigation installation.
3. "Turf Irrigation Manual"
4. A lot of guys usually start out by working for an irrigation company and then branching out on their own as they gain more experience.
5. Manufacturers' schools.
6. Distributor seminars.
7. The Internet.
8. This forum. (better have thick skin)