Business is business. I think part of your answer has to take into consideration the basic business principles. And the most basic starting point is writing a business plan.
There are plenty of sources for information on how to do this, online, books, your public library, State small business agencies, and Federal small business agencies. A lot of your specific business plan will deal the the specifics of your catering business, but it will also include things all businesses must deal with. Try to be as realistic as you can, and take into account all the formal requirements like licencing and insurance for example. If you have to cut corners in order to turn a profit, you would never survive if your business expands.
I took a business class put on by our Small Business Development Center which was underwritten by US West and a couple of banks. This lowered the cost to about $150, and they had 7 or 8 night sessions that were 3 hours long. We learned about a business plan, how financing works, taxes, payroll, unemployment, profit, loss, liability insurance, etc, etc. By the 4th or 5th session, everyone in the class had a draft business plan. They arranged for speakers to come in and give a talk and answer questions. All in all, it was a good learning experience, and I was a business owner/partner for 40 years.