A business without customers might as well not exist. In fact, no business will last long if it can't reach prospective customers to convince them to become paying customers.
Your business, too, must have a process for generating sales leads and converting them into customers. Traditionally, that process has been modeled as a funnel.
However, whether a funnel is the best way to conceptualize the process and match the customer journey has come under question in our Digital Era. Nevertheless, it remains a time-tested tool that works for many businesses.
The most important lead-generation success factor is a deep understanding of your potential customers' needs and wants at various stages of their journey to buying from you and becoming your customers.