Writing a proposal is a little like writing a resume, except with a lot (lot) more information. You want the details, style, and tone of your resume to align with the personality of the company that you are applying to, and the same is true for a proposal. If the company hates the proposal, they will probably hate working with you.
This, however, is not necessarily a bad thing. Think for a moment: have you ever had to work with someone that hated you? If so, remember how awful it was for a moment. Remember how you didn't really like them either, how every meeting seemed to take three times as long as it should, and how, when you went home every night, you said you yourself, "I'm not getting paid enough."
A great proposal will help you win the best contracts, and avoid the contracts that are more trouble than they're worth.
You want your proposal to reflect you, your company's culture, and your values. But you don't want to take it too far. If you are laid back, fun-loving, and good natured--show it! But maybe don't include pictures of Disney characters and screenshots of your latest video game win.
Here are a few strategies to help you show off the real you without crossing the line on unprofessionalism.
Do they need to know that you take your staff out for pizza and a movie every other Friday? Do they need to know that your company has been nominated for 18 awards for graphic design? Do they need to know that your main point of contact is currently on disability leave?
I don't know. Only the client knows that, and the answer to this question will likely depend on the personality of the person reading the proposal, the type of work you are doing, and the company culture on their end.
What you can do is cut back on the extraneous details that don't provide any value. This includes things as small as individual words--breakthrough! innovative! first-rate! cheap!--to entire phrases: "We might be able to possibly give you the quality you are looking for for the price you are looking for." (Don't write that.) You may even consider cutting entire sections if they don't seem too important.
Get rid of words like etc. or very or really. Focus on bringing the most important concepts to the surface. What do you want your potential client to remember? Say those things first.
It doesn't matter how friendly, professional, mainstream, or ahead of the curve you are--if your proposal does not offer a solution to the problem the client is trying to solve, they won't accept your proposal. You may choose to include some light information that isn't crucial to the contract but gives an idea of who you are and what your values are--but don't forget to include the solution.
Always answer the question: How can you provide what they need?
A client will look at your solution first, and your personality second. If you and another potential recipient of the contract offer similar solutions, but your personality is more in align with the client's, then you will win--and vice versa. So definitely include your company's personality and values, but make sure the solution rises to the top.
The last thing you want to do is make the client work to figure out what you are trying to say to them through the proposal. Include what they need. Get rid of extra words and ideas. Focus on the solution.
Don't make them dig.
This can be done in a variety of ways. Watch your language: don't use too many 5 cent words or long, rambling sentences. Even if they aren't run-ons, long and rambling sentences can easily lose a reader. Keep things short--get to the point! After all, that's why they're here in the first place.
Focus on organization. If it doesn't follow a logical progression of ideas, the reader may give up and walk away. Likewise, too many flip comments or too much heavy-handed language interspersed with the important details can also cause your reader to walk. Make sure it is organized in a way that makes sense.
Adjust the formatting. Using things like headers can make it easier for a client to read through the document without getting lost or drowning in too many ideas. You can include a table of contents if it's a long proposal, or use bullet points, bold, and italics if it's a short proposal. Make any numbers easy to read and understand. Keep your sentences and ideas concise and to the point. Add a few graphics--pie charts, bar charts, or line charts. Maybe throw in some pictures or bubble chart.
The most important thing to remember, however, is to be honest. Don't lie about your company's qualifications. Don't offer to do something that you can't do, or that you aren't capable of completing. Be honest in your proposal, and be you.