Why build a database?
It is almost always easier to sell a product/service to someone with whom you already have an existing relationship. Even easier if that relationship is positive, and easier still if you have taken the time to develop a clear understanding of your value proposition and how it can benefit the prospect.
Building a database of potential clients takes time, effort and typically an appropriate CRM (customer relationship management system) to manage it, but once the process is in place and working, engaging with those clients and identifying which ones are ready to be sold to (as opposed to sold at) is both easier and ultimately significantly more cost-effective.
Lead/Prospect nurturing
The process of developing a lead or prospect towards the point where they are ready to engage with you and potentially buy can be short or long, depending on the amount of trust required before a purchase/engagement, and that typically also relates to the amount of expense involved with the transaction. Appropriate content and development at various potential touch points (both virtual and actual) can speed up this process and make a positive ultimate outcome more likely.
Segmentation
By their actions/inactions and as a result of additional information that you may be able to gain along the way, it is possible to identify and focus your promotional activity on the most likely prospects. This both reduces the cost of promotion, but also reduces the potential to waste time and effort both on your part and also (and importantly) on the part of the prospect. It is vital that you treat the inbox of your target audience with respect, so as not to reduce the trust that you want to build with them.
Systems
Identifying and implementing the right systems to support this effort is not an easy decision. Some are more complex than others, while cost is also clearly a major factor. Furthermore, the integration of these systems with your team and existing processes and systems also need to be considered carefully.
Help!
The upside in cost, business scale and efficiency are enormous if done properly. The potential waste and frustration, when it is done poorly are significant. You need a partner that has done this many times over, across a variety of organisations, both in size and industry.