Since your mission statement is only a few pages long, your executive summary will allow you to further expand upon key points mentioned in the mission statement. Consider including your business history, biographies of key players, an overview of the business including locations, employees and available products and services. You can also discuss goals and future plans. Use this section to really draw in the readers.
Another point of contention is how optimistic you should make your business plan. The problem with making over-optimistic predictions and plans is that these plans could well go wrong. Unforeseen circumstances can always put a spanner in the works. Therefore, it's wise to err on the side of caution when it comes to devising your business plan. Indeed, it's wise to predict conservatively and prudently when it comes to assessing the possibilities of future targets, sales and profits. A worst-case scenario will always prove to be less of a shock than one that raises expectations too high.