It's important to be constantly experimenting with new channels and tactics to cultivate fresh business opportunities. Whether it's the ads that will begin appearing on Instagram or covering new ground within the Google Display Network, there are always emerging opportunities to test.
When trying out something new, the chief goal is to figure out whether it can deliver sales / leads of an appropriate quality, at an affordable cost.
Inevitably certain lead sources will work well for a period of time, then become less viable. In the early days of Google, pre-AdWords, companies were able to buy the top positions on Google's search results for a fixed and relatively nominal annual fee. This was an early bonanza for many marketers (including MoreVisibility) as it provided prime positioning without the auction / competitive component that drives SEM pricing models (and Google's revenue) today.
Diminished effectiveness within any channel could be caused by greater competition, rising costs, changes to their rules, etc. Other times, we've seen a quality drop in the channel itself (see LookSmart circa 2004). With history as our guide, it's extremely important to accelerate activities in any channels that show promise, as the dynamics are likely to change sooner rather than later.
On a related note, fine-tuning a plan to maintain contact with those who convert off your marketing efforts is really important. Your lead generation undertakings are an investment in your prospect database and should fuel a pipeline of new customers. Whether it's through in-person meetings, email, telephone, traditional mail, social media, or horseback, be sure that those who make it to the top of the sales funnel get the best possible attention moving forward. You have much more control over the process after a lead converts than you do over how many leads you will be able to derive in the first place.