At least you have the right idea. You need to start capturing leads asap.

You have to be in control of the process.

You need to obviously research the market which usually means researching keyword
demand. Just because some one has created a product doesn't mean it'll sell or is selling.

Obviously if capturing leads is going to be your focus, you'll need the necassary components
such as:

Lead Capture Landing Page (squeeze page)
Autoresponder (Aweber,Getresponse,1SC)
Free Incentive (report,audio,video,newsletter...)
Follow Up Email ContentSeries