Build on your organization's achievements and emphasize its capabilities, but don't misrepresent them. Be specific, don't make sweeping statements, be certain that your conclusions follow from reasoning, and never reach an unsupported conclusion. Make it easy to read by listing all the benefits of your idea. Meaningful and clearly identified involvement is the goal, without having the funder drive the process. Funding proposals should not be excessively long.
Length depends on the nature of the project and the funder's decision-making process.
You are in full control of the proposal development process. You set the boundaries. You can be selective about the people you involve and the amount of information you divulge. Write proposals using simple and understandable language. Where appropriate, use the language of the funding organization to secure leverage, or change language to match the purpose of each given section.