To successfully reach business goals, marketing and sales must work hand-in-hand. JDM's approach to marketing uses a sales and marketing pipeline process based on multivariate statistical models and hard data.
Wow, that's a mouthful. Let's break it down.

Suspects
Suspects are pre-qualified leads from the "Universe." Leads in this SPOC zone have, by all available data, qualified themselves as being affiliated with possible new customers.
It should be noted that Suspects don't have to be Decision Makers. They may be Influencers, future referral partners, whatever. The point is, don't market to everyone. Market to everyone who may help achieve your marketing goals.
Prospects
In Suspect-level marketing activities, you're trying to get your list of Suspects to raise their hand. Once they take a favorable action, allowing you to qualify them as Decision-Makers, Influencers, etc., then they transition into the Prospect zone of SPOC.
Prospects are potentially valuable sales leads, but not yet ready for the hand-off to sales team members. They need to be warmed up, educated, and make one more leap before they're ready for sales to "roll the pen."
Opportunities
In this stage, marketing has qualified, warmed, and educated sales leads and handed them off to sales team members. However, marketing can't stop there. The message may change in this zone to more of a sales-focus, but these leads will require sales-support marketing activities to cross the finish line.
Customers
Once your sales leads have passed into the Customer zone, it's important that marketing not forget about them altogether. Marketing can still provide tremendous value as an up-seller, a cross-seller, and in customer retention. Remember, it's not enough for marketing to send a "thanks for your business" card when keeping customers is usually more profitable than losing them and finding new ones.
Conversion Ratios
As mentioned before, JDM's SPOC approach uses statistical models and hard, observed data to determine how leads will progress from the Suspect zone to the Customer zone. We call this transition percentage, a "Conversion Ratio." Once calculated (or estimated for early campaigns), we can determine a sales and marketing budget that will generate a positive ROIm as well as the most efficient marketing mix.
Learn more about this approach to budgeting for positive ROIm in our "Backwards Marketing Budgeting" tip.