There is an incredibly useful tool on the FIRST website under Team Resources called the Volunteer's Handbook. It should really be called the "Guide to Solicitation for FIRST" because that is exactly what it is. It is a handbook for anyone who wants to start a team or needs to approach a school principal, college or university or a potential corporate sponsor.
The sections are divided by the target of the solicitation. There is one for school principals with all the arguments to make and what it takes, another for potential corporate sponsors, and another for colleges and universities.
Each guide has 3 basic sections. The first is the list of all the reasons for and benefits of having a team. This should help you when making your pitch by phone or in person. The second section is "What It Takes." Anyone who is interested will undoubtedly ask what the program will cost them in terms of money and manpower. It is all laid out neatly here. The third section is what to say to overcome the most common objections raised. This should help you address any of the concerns they may raise.
Please note that many of the sections are WORD documents. This was intentional. Use them, change them, delete sections, add sections, do what ever you like to create a handout for a potential sponsor that works for you. There is even a team brochure you can modify to make your own.
Check it out. I think you will find it very helpful.
http://www.usfirst.org/robotics/volbook/