Two important lessons about having business cards at trade shows/conventions. The first one is obvious: always have them on hand. Always have some, even when attending a social activity when that activity precludes handing them out, such as skydiving. If you leave them behind, you will encounter someone that could be a good contact just as you achieve terminal velocity.
Serendipity is good fortune in making unexpected and fortunate discoveries. Like my friend suggesting we all go to The Tucson Festival of Books just as I’m preparing for a networking conference with a goal to work with book layout. The timing on this, and all the other little things one needs to do when starting a business, is falling together perfectly.