Search engine optimization can take awhile to get going, as can other lead generation techniques. While they are the best, and while some experts saying purchasing leads is a bad idea, it's not always the case. Buying leads from a trusted source within your niche can actually be extremely beneficial...
Analyze the numbers surrounding your lead generation. Are you finding it takes lots of hours to discover potential leads? Are these leads qualified or rather weak? Measure the time you have in versus the conversion rate. This will help you decipher which tactics give you the best return on your investment...
Test a small market sample if you are trying to generate leads in a new way or area of consumer spending. While online marketing can be very economical, you don't want to waste a lot of resources on something that's going to go bust. Test a sample and if it generates a few leads, go for it! Otherwise, simply live and learn and move on.