We started with development for iPhone and iPad, and Apple has this huge list of requirements, from a dozen icon app sizes to how you specify your legal entity and your banking information, to how your app is described in the App store, to which graphics you are allowed to use. This is in addition to the business plan, setting up a YouTube brand channel, a Google+ profile, and whatever else I have already done that I forgot about.
I also had a meeting with my business consultant, Sean Duncan, who confirmed that I was on the right track, and made sure I had addressed several possibilities that business owners often overlook. (Fortunately I attended one of his seminars years back, and remembered to write down almost every word.)
And last but not least, I have been networking, networking, networking! I've been out there promoting my new company tirelessly. Fortunately, I have had a fantastic response from everyone I have talked with, so with a little luck and a whole lot more hard work, I hope to be actually selling my first app next month.
The takeaway: It's a whole heck of a lot harder and much more involved than you think it is going to be.