1. NEVER cannabalize your membership! Don't plan to sell something that only members of your sorority would be interested in.
2. If you spend $5 to make cookies, plan on making AT LEAST $7.50. Even better is 100% profit. If you find that unethical, most department stores charge over 200% profit.
3. Try something that you can go to each dorm, sorority/fraternity house to sell, is cheap, and will be wanted. Good things include chocolate bars, half-dozen or a dozen cookies, etc.
4. If your school allows you to set up a table or stand, do so! You'll get everyone on campus that way. Dress nicely!!
5. ADVERTISE! "Bake Sale - January 1st - Student Union Lower Lobby - 8a-6p - benefits (charity) - Held by XYZ Sorority", on posters & in the Student Newspaper.
6. With enough advertising,
fresh doughnuts in the morning work VERY well! This can also be done with order forms.
7. Decide how much you plan to make prior to event, and don't stop until you've made AT LEAST that much!
8. You only have six members, you cannot afford to burn out!
9. Plan to hold one of these events a month so people get used to them.
10. There are a lot of ideas for Valentine's Day - sending lollipop messages, rose messages, etc. They're very successful, but very time consuming. If you can use some of your younger (biological) sisters to help, do so!
11. Good luck!

Feel free to PM me if you feel the need!