A fundamental premise that the web and search in particular have been built upon is that the "buyer" comes to you (your website). That's true relative to earlier channels of marketing like outbound telemarketing and direct mail, but for a large portion of businesses, particularly B-B companies, utilizing the internet to cultivate new prospects is the beginning of the sales funnel, not necessarily the middle or the end of it.
Given that a one visit close isn't realistic for many businesses, it's essential that significant attention be spent on staying in front of those who have made it to your site and somehow self-identified. Ways to entice visitors to provide their email addresses center on offering a valued incentive like a whitepaper, webinar, etc. Newer age tactics to establish a lasting connection include the follow / connect Social Media options.
I encourage you to implement ways to easily attain visitors' email addresses on your site. Building your list may not be as hip as gaining followers on Pinterest or LinkedIn, but at the end of the day it may be a whole lot more valuable. Right now, everyone is chasing social media and reallocating limited resources from channel to channel. For most businesses it's not possible to pursue each new social media opportunity in a meaningful way, with unique content, engagement ideas, etc.
It is possible, however, to keep it real simple and create well-targeted emails that speak to different segments of your prospect audience. Experiment with various messaging (calls-to-action), personalization, formats (text vs. html) and frequency. Don't bombard your list, but keep in front of them a couple times each month. It sounds like an old school concept, but if managed correctly email marketing can still be a significant contributor to your bottom line.
For a cutting edge update on the social media landscape, please read Danielle Leitch's article in this month's newsletter to learn about new video offerings from Instagram and Twitter. The right marketing tactics for any organization are the ones that perform cost effectively. Keep an open mind to more traditional channels like emailing your database while experimenting with the newer social channels as well.