You need domain knowledge, you need sales, and you need marketing.

At my last gig, i asked my boss about developing a mailing list. he said it was "done". I didn't push further, but thats just not how mailing lists work.

find a channel or a few channels and develop a presence. You're building a relationship, not just selling something.

get their info. ask for it. on a web form, on the phone, and in person. Keep in touch with them. Do drip marketing. Get them involved.

Word of mouth, blog posts, tweets and facebook pages only carry you so far. For some, its plenty far enough. For others, they need to inject more hustle; cold calls, chance meetings, going door to door if need be.

Know how to hustle your customers; what they want, what they need, and what they'll pay.