Almost any business engaged in providing goods or services will at some point have to reply to a Request for Proposal, or RFP. The biggest mistake in writing a proposal is to approach it as a fill-in-the-blank task. A project proposal is more a function for the marketing department than it is for the technical or managerial staff that will actually be engaged in the task after the proposal is accepted, as the purpose of the proposal is to convince a partner to hire your firm above the potentially dozens of others who are also submitting proposals with probably lower costs than you.
The initial RFP will contain a lot of details and questions, and possibly some background on the company making the request. If the RFP is done right, it should give you just enough information to craft an adequate response; however, adequate won't win the bid. A generic response that does nothing more than answer the questions is not enough -- you need to dig deeper to answer the questions that weren't asked. Take time to understand more about the company, and do some research. If the requester is available, ask him meaningful questions, and ask for clarification if it is warranted. This will not only help you better understand the task at hand, but also to come up with a price quote that more accurately reflects the client's needs.
Know What the Client Really Needs
More often than not, clients don't really know exactly what they need, and their true pain points may not be reflected in the RFP. Take time before responding to understand the client's core business, the primary challenges of its competitors, and who that business's other suppliers and partners may be. Ask yourself what the driving force behind the request may be -- if you can solve a problem rather than just provide a piece of equipment, you will move to the head of the line. Anticipate what the customer wants today and what he is likely to want next year, and plan out different scenarios before writing your proposal.
Sell Yourself and Your Company
Most requests for proposals aren't just looking for the cheapest provider -- clients want someone who understands their pain and will solve all of their problems. Your job is to convince them that you are that person. When writing the proposal, don't just stop at making a list. Each bullet point or deliverable should include at least some minimal language as to how you are solving their problem, or how you are best and most uniquely positioned to help them.
A good sales tactic in making a proposal is to offer options. If you have taken the time to truly understand the client's needs, you can offer a range of solutions -- usually three is best, because people have a natural tendency to pick the middle one. This lets the client know you are flexible, and also capable of handling needs that may go beyond those requested in the RFP.
Not all proposals are the same, although if you write many of them, you will find that it becomes possible to re-use much of the same language. Generally speaking, a proposal should begin with a personal cover letter, and then proceed with a summary of the project to ensure you and the client are on the same page. Include a section on overall strategy as well as a section on individual tactics and deliverables, and then include a section for overall costs broken down by deliverables.
The client may have specified a delivery date, but it is always a good idea to break that down into a more detailed timeline if there are multiple deliverables. The proposal should also include specific payment terms and a signature page. A paragraph or two at the end for an about us boilerplate also gives the client a little more information about your range of services and background.