Way back in 1998, Tom Younker was phasing out of his computer programming practice (as most of that work was then being outsourced) and moving into technical support. His accountant recommended forming an LLC and opening a business checking account. That was the official launch of Dare Computer, LLC.
Today, Tom's still running the company, and has had an assortment of assistants and trainees over the years. He's also developed ongoing relationships with other professionals in the tech support arena. So, if a Mac job is more complex than he's comfortable with, he calls in a Mac pro. Likewise for Windows Server issues, notebook motherboard replacement, etc. Any job that his 17 years of experience hasn't left him comfortable with, he calls for help or refers to another professional. Likewise, his circle of contacts calls him in on certain MS Windows problems, networking situations, or Linux desktop or server issues.
in this business, you just have to read and study every day, pay attention, and have a good head for details! Plus patience --- don't neglect that virtue.