It's not:
Am I selling for the right price?
Is our feature set explained?
Can I get the product to the customer quick enough?
Should I be involved in social media?
Does my website have enough SEO?
Am I promising enough?

No, the most important question in marketing something to someone who hasn't purchased it before is:

Do they trust me enough to believe my promises?

Without that, you have nothing.

It comes down to credibility. If the potential client knows about you, but hasn’t purchased from you, then you probably don’t have enough trust. In fact, if your value proposition is solid but sales aren't being made, look for trust issues.

So, now you’re worried about earning trust or building credibility.

Well you don’t need to. There is one very simple, time tested, low cost method for building the credibility of your organization. That’s public relations. 

Whether you do it yourself, have an in-house expert, or use an outside agency, trust is best build using long-term public relations. Why? Because PR uses a third party voice to add credibility to you. No other marketing tactic can achieve this.