i ran a successful small business for 12 years. in my opinion, you must learn by doing. it's scary but you have to do it. the problem is every business is a unique snowflake and you're not going to find much general advice other than "buy insurance" or "outsource your payroll and HR."
one strategy i used was to sit down and think of all the things that could possibly go wrong with your business or a specific project, and google for solutions that can help you with that. work backwards from the problem. it's like designing a resilient software or systems architecture.
you're going to read a LOT of federal and local laws, accounting rules, insurance regulations, speak to a bunch of different solutions vendors, and wade through a bunch of bullshit before you find the one nugget of information you need.
you also need to be generally savvy about how to deal with money and people. naive people don't make it very far.