I am fairly new too (at least to creating my own business) … and I have definitely learned that it’s a trial and error.
One book that I have found useful was Hill’s introduction to the business. It is written in such a discursive way that you can read it through quickly and then stop and go back to the important bits.
You can get it second had on eBay I think.
But starting a business is a strange combination of creativity and rationality. You need to think both of what you like doing best, and where it is likely that money will come in from.
I know there are mixed feelings in the community about it, but I decided to be a SubVA (or “Associate”) to a well established VA firm for over a year before going solo.
This post written by Caroline is quite useful to understand it better and maybe dispel some of the confusion about it all:
Hope that helps a little to start off with.