Successful viral marketing is no easy task. Many viral marketing initiatives never get off the ground. For every Old Spice there are thousands of failed campaigns.

It may seem obvious, but not everything is ‘viral worthy’. Your product, service or message needs to be catchy enough for others to want to share it.

In math terms this catchiness would be described as a viral coefficient – which is basically a measure of how many new audience members are are communicated to (with your message) by each existing audience member.

Having a viral coefficient of 1 means that your message will spread at a constant (linear) rate. For every one person who hears your message the message is shared with exactly one other person. Alternatively having a viral coefficient of less than 1 means your message will spread for a little while and then eventually die out if no further communication happens from the source. And, conversely, having a viral coefficient greater than one means your message will continue to spread throughout a network without any further input.

For those non math folks, this means the catchier your message is the longer and faster it’s going to spread without further input. This seems intuitive, but so many marketers forget this basic idea.

Provided below are three quick rules for increasing your odds of viral marketing campaign success:

1. Have something worth sharing

Content that has a high viral coefficient includes: real-time/live news (especially accidents, disasters or major events), gossip (celebrity, political, local), secrets (access and insider tips), controversy and emotion (funny, violent, sad).

Content with a middle-of-the-road viral coefficient includes, ‘how to’ blog posts/videos and news articles/commentary.

The least viral of all content includes ‘about us’ web pages, corporate promotional videos and any other selfish content.

2. Make your message easy for people to share

Having a highly viral message is a good starting point in any viral marketing campaign, but it’s not enough. You also need to ensure that your message is easily spread.

There are many free tools such as AddThis or ShareThis that you can place on your content to provide an easy hook for your audience to use. And, many common web 2.0 tools provide sharing capability built in (Youtube, Facebook, Twitter etc). Use these tools – they’re free and easy.

Also, don’t forget that basic human biology has a strong affect on your viral coefficient, as there is a limit on our short-term memory and attention. Keep your message short, as nobody will bother to read or remember it if it’s too long.

3. Seed the network

Finally, and most importantly, all viruses need to be seeded to an initial population before they can be spread throughout a network. The larger the seed population the longer the message will spread through the network. The size of the seed population needed is inversely related to the catchiness of your message. If the message has a high viral coefficient then it’s ok if your seed population is small as the message will spread far and fast with little input. However if your viral coefficient is low then you need a larger seed population to penetrate the network.

If you have trouble remember these rules just try to remember how the common cold works. Colds are highly contagious, they are easily shared and they spread faster in places of condensed populations such as movie theaters and elementary schools.