The best lead gen is either paid or inbound.
- Google Adwords
- Email Newsletters (Local)
- Create videos on youtube for relevant search terms
- Blog about the things your customers are searching for
- Create interesting infographics relevant to your target customer / geography
All traffic should be pushed to a landing page and optimized for conversion to email.
I do agree with what Dan Martell said, those are good general lead generation strategy tactics to employ, but you have to study your target market and make sure you're understand what makes them tick, what concerns they have as property owners, and understanding what they have to go through.
One thing I would add is creating ebooks relevant to your target market. For example, How to Sell Your Property in One Month. It's something you can effectively promote in channels outlined by Dan, and then call them up to see if they need help professionally listing and selling their property quickly.
One real estate specific tip I can provide is looking for leads of already listed properties that have been on the market for a while.
Some of them might be coming off market due to agents inability to sell/rent it, so you can try to get them to pick your clients to list their property.
Even if it's still listed, you can always see if owner wants to change agents to sell/rent it quicker with different strategies. Depends how aggressive you really want to be.
Another less popular lead generation tip is using Craigslist to look for DYI listings and calling them up to offer hassle-free professional listing service. If done right, it can be effective.
Direct mail can be effective if it's done right on a local scale. Instead of focusing on services, use sold properties to show clear results and tie that into recipient's property. For example, "We Just Sold 2 of Your Neighbors' Properties" with images of properties.
Your lead generation efforts really depend on your budget and what you're willing to do or hire someone to do. To be effective with content marketing you do need industry expert(s) to ensure you're producing good quality content that's correct and useful.
Zillow and Trulia both offer lead generation products for realtors; you might be able to scrape, or pay, for leads from there using a combination of tech and pay-for services. You might also consider checking out what data sources @Factual has that can be tapped to reach the right audience... but yes, inbound is way better than cold calling fo sho