You also need to learn a multitude of other skills such as time management, people skills, how to hire staff and, most importantly, how to grow your business.
You can get these skills in a variety of ways including reading, going to seminars, webinars and so on.
A great way to grow your business is to get a suitable mentor.
If you're interested in this option, take a look at this website: www.business.govt.nz