Riggle is right. I'm going to say they'd probably come down on you hard for it out in California too. However, if you are legal to fertilize, a thick lawn is your first step in weed prevention no matter what program you decide on. Being that you are still in High School, you may not be eligible to take the test yet. You have to start somewhere though and starting early is the best time. Learn everything you can. This site is a great place for that. There is a lot of $$$ to be made in this business. I have a cousin in Valejo that does mowing and light landscaping. If he was more interested and took some initiative, I could help hime live very comfortably offering weed control and fertilization in his services he provides to his customers.