Since your prospect is in control of the buying process, you need to make sure you are monitoring their online activities to know when they are ready to move to the next stage. Lead scoring determines where your buyer is in the funnel. Lead scoring should consider the prospects' interest level defined by their actions.
For example, track email clicks, ebook downloads, web page visits, etc., and update scores accordingly. Also, be sure to score assets differently depending on where they are in the funnel. You might score a pricing page much more than an entry level ebook.