I'm brand new to the business, people are gonna ask me to fertilize. I live in Houston and am taking care of 5-7k sq ft lawns, all st.augustine grass. When should I fertilize throughout the year, what should I use,what should I charge? Also, any tips on doing a good job? Any other things I should spread along with fertilizer? I know this is a lengthy question, sorry. thanks for your input!!!!