Requirements for selling T-Shirts in California?

I wish someone would create a website with step-by-step instructions on exactly what you need to do in each state (and eventually per county/city) and what order to do it in to became a normal, licensed business. Most websites that offer this kind of information merely have a link to the local governmental websites for whatever you are trying to register (sales tax, business name, etc). The local websites here in FL leave most details out and say you should come into the office to discuss what you're doing. I think that if you're doing something simple, like "I'm going to sell heat press t-shirts" or "glowstick vendor at the 4th of July show" that all the information you should need should be on the website. I've been to two "small business startup" seminars to learn this kind of thing about a decade ago, and walked out on both of them when they started talking about stuff like "do I need to move to a bigger building" and "how to handle payroll for over 20 employees". Yes, that's still a small business but if you've got 20 employees and enough work to need a bigger place, that's not a startup!!

I gave up on it back then and did small amounts of internet eBay sales instead, all out of state. For the work I do now I've claimed as a sole proprietorship, and since I do on-site non-tangible work, I don't need a building/zoning or sales tax license. Now that I'm debating starting a new business again, I'm getting annoyed by the lack of clarity on how to go about everything legally. I'm still very confused on the zoning ordinances since I'm planning on doing internet sales and vending at conventions, no local shop or sales (other than word-of-mouth/delivery). It says you don't need it if you're not actually having customers at your house but you do need it if you have tangible property... so is that a yes or no? Whenever I'm less annoyed I'll go in there one day and try to figure out just what to do, but I wish I could do it all online or by fax. My boss' nephew is in the process of launching his own business and she's been trying to help him but they've both basically given up and her suggestion was to find someone who specializes in doing it. Ugh. I rather suspect California law would be even more confusing than Florida law, especially since your t-shirts may cause cancer in lab rats if they eat 5000 shirts a day.