Social media channels can be a powerful medium for generating leads and converting them into actual sale. The article covers few sure shot tips that will help you get some hot leads from various social platforms, at here : http://www.brainpulse.com/articles/social-media-marketing/generate-quality-leads-with-social-media-marketing.php
You always need a sales funnel even for email leads. The best way to get leads is offering free stuff, coupons, discounts or newsletter that inform customers about your newest giveaways. People love getting things for free, so always use that for your marketing.