What you offer mostly depends on who you're mailing to.
This is also a pretty easy puzzle to solve.
Regardless if you're a B2B or B2C, your target should be the same type. Along with blanketing the general population, you should always target the new comers, new businesses, new homeowners and new movers.
These newbies always need and want products and services. New businesses and new homeowners particularly!
A good example of targeting a new homeowner and what to offer is: You're Joe's Pizza and you sent a postcard to the neighborhood. (It's good getting the new people that are replacing the the old, this maintains your market share). A solid offer is giving them a FREE pizza the first time in, it's also a perfect time to log their their personal information, birthdays, anniversaries, kids names, etc. The first reaction is a FREE PIZZA, are you nuts? Do the math - if you figure that a good customer comes in at least once a month and spends $20 that's $240 a year, not a bad return for the cost of one free pizza.
You can't be afraid of giving something away, the return is usually far greater than the initial cost, and keep in mind, you're not mailing this free offer to the general public, just the few new comers.
Remember, usually, the greater the offer the more reaction you get.
Next time you see a member of your Chamber’s staff, thank them for making this valuable information free to you.