Use website links that have embedded web analytic codes. You can do this through your website provider or with a free Google Analytics account. Make sure each strategy uses a different link, so you can track your most successful lead gathering strategies. Most web analytics programs will automatically mark down leads that come from major search engines.
If you're wondering what a sales funnel is, simply imagine a real-world funnel. At the top of that funnel, some substance is poured in, which filters down towards one finite destination. In sales, something similar occurs. At the top, lots of visitors arrive who may enter your funnel. However, unlike the real-world funnel, not all who enter the sales funnel will reemerge out from the other end.