If you want to lead nurture the first thing you do in know your target market well and thoroughly. Thinking that buying email lists will get you clients and byuers is crazy and still so many do this. Promote a seminar, a contest, or a sale to lead capture. In the seminar idea ask them to provide contact information for futher communication (in a Feedback form for the seminar, for example). This way you also get their consent for emails.