CommunityWho and where is the community that you'll market to? If you can say "Surfers on Facebook" or "Romance authors at books.com" then you're way ahead of the game. Or, if you have an email list, which is an audience, that's good too.
Content
You've got to have interesting and compelling content, no secret there. It can be great photography, a children's story, a video documentary, or a guitar lesson. Later I'll talk about good production when it comes to video & audio. Test the content by sharing with someone who is in the target community, preferably NOT a friend so you get honest feedback.
Control
Do you have (or control) the sales rights to what you are selling? Sounds obvious, but you need to confirm. The place where most people get into trouble is either by using music without the rights, or shooting video in a venue that is not a public area (like in a sports arena). If in doubt, check it out.
Credibility
Sales are tied to your credibility. If you're a known and trusted voice, people will be at least familiar with the name, so lowering the barrier to "yes". If not visible, start publishing free portions of your work to gauge your reception and so people get to know you.
Continuity
Once is not enough! To build your business, you must commit to continue publishing. Think of them as consumables, so that after each one, people are ready for another one. It may be daily, weekly or monthly, but the more you produce the more revenue you stand to make. After the first few products are out, it's common to feel like "this is alot of work". That's where most people drop off, never to be heard from again. Plan your production schedule and work your plan!
