The most important thing to consider when writing a plan is to take your time, be thorough, be accurate, and above all, believe in yourself and your product. Don't just rely on a sample plan, create a proposal that you're proud of, and that you are convinced will compel others to help you realize your dream.
On the subject of finance, you need to produce realistic financial details. How much money will the business require? What are the expenses required? How much tax will you need to pay? What are the profit margins? Do you stand a good chance of achieving these sums, and how? Finance plans should include income statements, cash-flow statements, balance sheets and profit analysis. This should form a big part of your business plan, in order to convince the vendor or bank manager of your credibility.