RFP is the first step towards your contact initiation and strategic partnership. Indivisual freelancers generally do not understand the the RFP, RFI and proposal lifecycles. It is a very assessment tool that you can leverage to find the right partner (or vendor or outsourcing company) for your fulfillment.

If you working with designers and individual developers it usually easier to start with Quotes/Bid than RFP. RFPs can be elaborate.

A great example of an what an RFP can include is at
http://www.entrepreneur.com/formnet/form/1173

Now, this is rough framework. You can tailor it as needed. When you go with RFP, you will receive proposals or RFI. There are tools and techniques to address that too.

Let's say you get 10 proposals. Each company with different rates, company size, geography, delivery schedules, milestones, development shop infrastructures etc... it is a daunting task to pick the right one and negotiate a contract.

Hey, if you feel like talking to me on this. Let me know..

Some of things a details RFP should have
Checkout this slideshare.
http://www.slideshare.net/profwaynesmith/how-to-write-an-rfp-16123708

There are tons of templates available for fee or free. If you need help identifying how to tailor it, let me know..