If using a mailing house, make sure that they have a sample of the invitation and any additional inserts, with specific instructions on how to stuff the envelope. The invitation should always be on top. As everyone retrenches from the social whirlwind of the 80's, it has become much more difficult to attract attendance at galas and benefits. Even corporate events have to serve a useful function for people to invest the time to participate. Not only does the event have to be presented as special, the invitees should feel special to elicit a favorable response.
Little things do mean a lot.
By paying attention to the details of your invitation, you have taken a major step toward insuring the success of your event.