[Kristina]

Keep it polite 'n professional but make sure it sounds like it was written in the voice of students, not an adult doing the work for them.

Few things that we usually cover in our letter:
1. What is FIRST
2. Who the team is, any accomplishments (or since you're a rookie team, any kinds of projects you are working on), how it formed, why y'all are involved
3. Why you need sponsorship; specifics are good so they would know where exactly their money is going to.

Since businesses get hit up for sponsorship all the time, keep it short and concise, invite them to a meeting, and make up to follow up with phone calls or visits to their HQ. Also if you want to be creative (and esp. impress a tech company), we made a lil team video/information thingie on those mini-cds. We also have team brochures. hope that helps.