Over the past couple of years, QR codes have cropped up everywhere from billboards to ketchup bottles.

They became the must-have gimmick for marketers, even when they didn’t actually offer consumers any relevant or useful content.

In recent months frivolous uses of QR codes seems to be less prevalent as marketers have realised that people don’t scan them in huge numbers, if at all.

But that doesn’t mean that QR codes are useless. We previously reported studies which show that 19% of UK consumers have scanned a QR code, with 3.3m people doing it in Q2 alone. We’ve also found several examples of QR campaigns that worked well.

So if you’re considering using a QR code in your new ad campaign, here are eight tips that you should consider before you do…

1. Make sure it serves a purpose

This seems to be less of an issue in recent months (or maybe I’ve just stopped noticing them), but QR codes are still often used in adverts without any discernable purpose.

So before slapping a QR code on your next magazine ad or bus poster, think about what it actually adds to the user experience.

Are you allowing them to access product information or maybe a discount voucher? Is it something that people will go out of their way to stop and scan?

I recently passed an estate agent in London that put QR codes on the property ads in its window, which is a great idea as it allows house hunters to quickly pick up property details on the go.

That’s assuming the estate agent adhered to the next rule…

2. Don’t link to a desktop site

The golden rule of QR codes is that you MUST NOT link users to a desktop site.

QR codes are an innately mobile experience so the content you want consumers to view must be mobile optimised.

If you actually manage to get consumers to scan your code then presenting them with a desktop site will undermine your efforts as they won’t stick around to read your content.

3. Placement

We’ve been quick to point out ridiculous uses of QR codes, and they are definitely worth taking a look at for a laugh.

But even if your ad doesn’t make it into a list of stupid uses of QR codes, there is still a danger that you will put it somewhere that people either don’t notice or can’t quite reach.

For example, if your code is on a massive tube poster don’t tuck it away in the top corner as people probably won’t be able to reach it, but equally people are unlikely to stoop down to scan a QR code that’s stuck in the bottom corner.

In reality people aren’t going to bother scanning your QR code unless it’s put on a plate for them, so think about your ad in the context of where it will be seen.

If you don’t think you’d notice it or be happy to scan it in public, then why are you using one?

4. Size matters

The absolute minimum size a QR code should be is one inch square, as not only does it make it difficult to scan but also people simply won’t notice them.

QRstuff.com says that the relationship between scan distance and minimum QR code size is roughly 10:1.

So a 2.5cm (one inch) QR code printed in a magazine will have a nominal effective scan distance of about 250mm (10 inches), and a QR code on a billboard 20m (65ft) from the where a passer-by would be scanning it would probably need to be about 2m (6.5ft) across.

5. Use a URL shortener

The more data you try to store in a QR code the smaller the dots become, which in turn means it’s more difficult for smartphones to read them.

So in order to reduce the number of pixels and simplify your code it’s best to use a URL shortener such as Goo.gl or bitly.

This should then make the scanning process smoother and reduce the number of users who can’t access your content.

6. Tell users what they stand to benefit

Scanning a QR code is a bit of a chore, so consumers are highly unlikely to pull out their phone unless they know they’re going to get something in return.

Therefore it’s important that you give some information on what the QR code links to and, depending on who you’re targeting, possibly instructions on how to download a QR code reader.

Instructions for scanning the code can be a simple call-to-action along the lines of: “Scan to get 2-for-1,” or “Scan to read product reviews.”

You need to entice the user, so make sure the content you are offering them is worth the effort.

7. Test it!

Seems obvious, but it’s easy to assume that because the QR code worked when you created it in the office that it will work on your poster.

So once you’ve got your final product, make sure you test the QR code using different reader apps and smartphones from a range of angles and distances.

If you can’t get it to work in perfect conditions then it’s not going to work in a bus stop, and users will be extremely annoyed if their efforts to scan a QR code come to nought.

8. Track it

As with all new technologies, it’s important to track how users interact with your QR codes so you can use the data to plan any future campaigns.

If you use Google Analytics you can create a custom campaign URL to track people who have scanned the QR code, or you can use bitly’s tracking service.

However it should be noted that these shorteners can both be hacked relatively easily so third-parties can see your data, which is how we found out that 4,500 people scanned the QR codes on a TfL poster campaign.

To avoid these issues there are also a number of QR code services that both create the code and track the users, though these are likely to incur a cost.