The best thing you can do is learn about how to run a business and how to deal with people. Then decide if you want to own a business or work as an employee for someone else who runs one. No matter how good of a trapper someone is or how big a client base they may have, if they don't understand business issues like insurance, registration, licenses, taxes, basic accounting (credits, debits, expenses, revenue, etc.), marketing, determining services, creating pricing structures, and many others, it will be very had to make it.
Anyone can learn about running a successful business through books, seminars, classes, and mentors but it is harder to learn about how to deal with people. Once you understand what all is involved (choosing a business structure, handling money, determining services and their costs, selling jobs, etc.) then you can decide if you still want to go forward.
The biggest issue I see with new wildlife control operators is that they want to focus on the trapping aspect of the job and not much of anything else. It's kind of like when fur prices are high and suddenly everyone that knows how to set a trap becomes a "trapper". Those that understand the animals and locations will always outperform those that don't. Specific to wildlife control, keep in mind that trapping is a service, it is not a business just like fixing a leaking pipe is a service, it is not running a plumbing business. Yes, the business owner may need to know how to remove the problem animal and perform that service, but if they can't sell jobs, pay bills and still have enough left over to live on it won't matter how good of a trapper they are.