My DDs and I have done a number of bake sales. Here are a few suggestions:
Make things that look interesting. Iced sugar cookies always sold better than oatmeal cookies because they stood out. Instead of slices of carrot cake, we baked individual servings that each looked like a mini bundt cake (I got a pan from Target that bakes six of these at once). Instead of icing a cupcake with a knife, use a decorating bag with a star tip, then add sprinkles. (This blog has lots of inspirational pics of decorated cupcakes:
http://cupcakestakethecake.blogspot.com/)
Consider making something that people can snack on at their desk--something that isn't sweet, like chex mix.
We bought a few apples and bananas for dieters to buy.
Package things to look pretty. I used the clear cellophane bags (from Hobby Lobby cookie and cake decorating dept.) instead of ziploc bags and tied them with ribbon. We also arranged things in baskets and on trays.
Price baked goods in increments of 25 cents. It will simplify making change.
Have plenty of change on hand. We never seemed to have enough. Since you are pricing everything in 25 cent increments, you won't need pennies, nickels, or dimes.
Ask people who offer to bake things to bring them in wrapped.
On the day of the sale, have a knife, small paper plates, plastic wrap, and ziploc bags on hand because there will be people who bring things unwrapped. If your office doesn't have silverware, you might bring a box of plastic forks, too.
Hope that gives you some ideas. Good luck!