• by Victor Wong , Op-Ed Contributor, October 11, 2013

The value of an ad is determined by how well it generates conversions and brand awareness. In 2010, Dataxu, a demand-side platform specializing in media buying, ran a large-scale test and found that creatives are the most responsible determinant of conversions.

Today, consumers are using multiple devices, and advertisers must be able to deliver a consistently high-quality brand experience on each of them. Ad creatives can no longer be created for a single platform, and it’s no longer enough to be "mobile first." You have to be thinking multi-device. Yet developing a seamless cross-platform display ad campaign can be a time-consuming and expensive process that many small- and mid-sized companies simply can’t afford.

The following is a guide to creating an effective cross-platform ad campaign without the high price tag. There are multiple factors that drive up cross-platform campaign costs, and making the right tradeoffs concerning factors like the number of designs, formats, and sizes you need to make will help you spend your time and money wisely.

Designs – How many designs should you run for an ad campaign? One specific brand message for consumers requires only one set of designs. However, if you're trying to drive conversions or find messages that resonate with consumers, you need a lot more.

Formats – HTML or Flash? Each format requires you to build the ad differently. The best trade-off is to support only HTML ads and have JPG backups in the instances of slow page loading or browser incompatibilities. Most browsers support HTML ads so there is no real loss of audience by not building in flash. Alternatively, solely building in flash leaves out a large amount of mobile devices.

When working with HTML, you'll have to render the ad. CSS is the best overall for this purpose. It allows the user to make responsive ads that can adapt to changing screen sizes and types (retina/non-retina) and, it allows for smoother animations. 

Size – How many ad unit sizes should you support given the 20+ standard ad units available for different screens? In our experience, the following sizes have the right balance of most impressions on ad exchanges and great performance:

• 300x250
• 300x600
• 728x90
• 120x20
• 300x50

When you account for all of the above and make appropriate tradeoffs, you can see a general cost savings of about 50%, which gives your campaign an instant boost in overall value delivered.

After optimizing for costs, consider the actual gains on performance. We have determined several key best practices:

Logo placement: Put the logo on the left for brand impact -- recall is much higher here, and since people read left to right they are more likely to see it. If already a recognizable brand, consumers are also more likely to look at the whole ad. When employing animation, it is a good idea to have the logo load first. Make your logo stand out by using a nice dose of contrast between text, colors and/or images.

Calls to action are extremely important. Buttons or a clear marking of them makes a big difference. Build device-specific calls to action (call = mobile, sign-up = PC)

Localize. Mentioning the DMA or neighborhood lifts CTR 15%. Campaigns get a boost of up to 70% by including geographic information like location name or local phone numbers.

Right now, most people have cobbled Adobe Flash builder and some type of mobile-specific builder together. However, new options are emerging like responsive ads and cross-platform ad builders, which automate ad creation across devices. The more successful campaigns are designed well, and while creatives are the most important factor when determining value, cross-platform design is the driving force in today’s digital ad revolution and will ensure that your ad creatives look good no matter where they appear.