RFP Request for Proposal

Creating a Request for Proposal can be a daunting task I you don't have a guide to walk you through it. After all, all sorts of vendors will be answering with the hope of landing the deal. But what should the RFP include? What information should I require from the responders? Just technical? What about financial and organizational? What kind of communication techniques should I employ? Or in short, how do I create a RFP (Request for Proposal)?