But your idea may be so new that you may also need to talk to potential customers, host some focus groups, talk to an ad agency, or maybe even make a prototype and float it past some people. Be prepared to spend the time. Remember, it's not about the Plan but the Planning.
Not surprisingly all these individuals have been in the business game for a long period and understand what they're speaking about. While you are in the beginning stages which may be just what exactly you will want, a professional available to assist you to on your way.
Are there emerging markets or market segments? Where does this product or service currently perform best? Possible Data Sources: trade associations; trade journals; attorneys & accountants dealing with the industry; industry salespeople; state business websites; focus groups.
Appendix - Resumes of principals/management; letters of recommendation from current business associates/customers/suppliers; marketing research data; demographic data; leases or contracts in place or as promised; business licenses; price lists from suppliers; trade or industry articles or data; floor plans; information on subcontractors; liability insurance policies.