This is the point where the whole story begins. Keywords is something that should be elaborated obsessively in order to have a high-quality traffic in future.
Search engine marketing is based on statistics, therefore it is well-calculable. The funnel has to be designed at the very beginning, it will surely pay back.
A solid traffic flow is something one naturally expects to be a result of SEO and PPC ads. Having said this, it's crucial to track the traffic up to leads and eventually sales.