What is the secret to hit the target sales?

Follow SPT, i.e., segmenting, positioning, targeting.
Know your product and their customers and then bridge the gap in between them.
Understand the need and requirements of your customers, make sure your product fulfills them.

sales is dependent on the quality, usability, and effective product.
First the product has to be targeted to well pre-defined clients/customers/consumers.
Surveys and consumption patterns can be found by research of segmented end users to have an idea how many potential users of this product exists.
Then promote it via cost effective channel that you can afford.