Everywhere you look, bar codes that bear an eerie resemblance to Space Invaders are appearing. “Quick Response” codes, known as QR codes, can be found on posters, magazine ads, ice cream containers, and beyond. So what are they good for, and how can you make the most of them? Mashable has a post with tips; here are my thoughts.

1) Start with “why?”. Know what you hope to accomplish by using a QR code. “All the cool kids are doing it” still isn’t a great reason. Are you driving people to a mobile site? Supporting a specific promotion or campaign? The answer to this question is important.

2) Know what you want your customers to do. You need them to want to scan the code. Think about your call to action, and why a customer would want to follow it.

3) Think about where you’re sending them. A QR code is a mobile tool. Don’t send them to a regular website–send them to a mobile-friendly page.

4) Know what you’re measuring. It’s great to know how many people scan the code. Beyond that, though, take a look at how much time they spend on your site after scanning that code. Engagement matters here. And how does it compare to other avenues? Are other approaches–Facebook, Twitter, etc.–providing greater contacts and engagement?

5) Be creative. I was at the Santa Barbara Zoo this summer, and they had what I thought was a terrific use for QR codes: providing current video of animals that are likely to be asleep, hidden, or sedentary at the time you walk by the enclosure. Toys R Us is including them in their “Great Big Toys R Us Book” this year, to provide more information about specific products–and even to show some of them in action.