Well for starters, I'm sure you would need a contractor's license from your local state. Also, check your local irrigation supply houses. At least the ones around me have been a wealth of information.
Every city and counties\parishes has different permitting requirements.
So check your local governments. Make friends with a local irrigation contractor. You won't be able to do the big jobs, so you won't be a threat to His\her Company.
I didn't go to school, but grew up in this industry. Most of what I know is from experience and getting help from my local supplier, sometimes having to pay for this help.
The best advice that I can give is stay with brand products. (Rainbird, hunter, Toro, irritrol, hardie, k-rain and many more)
You may want to check out brand name web sites also.
I will send you a personal message with a link to a web site that should be helpful for you. I don't want type it now, as I may be violating this web sites posting rules.
J-LC Landscaping & Maintenance Gardening
C-27 CA. Contr# 770044