VIRAL marketing often means walking a fine line between spreading your brand name like wildfire and spreading it too thin. Even the phrase "viral marketing" itself sounds a little scary.

But it just is a form of motivated word of mouth that works offline as well as online. You encourage your customers to do the legwork for you by motivating them rewards such as contests or kickback schemes and the prestige of being associated with your brand.

If it is so natural and ubiquitous, what's so dangerous about viral marketing online? Here are some of the pitfalls and tips on how you can avoid them.

Problem: Associations with negative sites or people

You are an online book retailer with an affiliate programme. You get the referred sales, the affiliates get a reward. Let's say a neo-Nazi site signs up as an affiliate and begins featuring your books and you don't want that association. Working out the logistics of approving every affiliate, creating guidelines and monitoring can be tedious and time-consuming.

Solution: Choose who is worthy of the virus, limiting relationships

Use a moderated approach. Send surfers the information directly on how to link and what graphics to use. This gives better control of the graphics and more direct communication with those who would use the programme wisely.

Problem: Breaking netiquette (spamming)

Phonefree.com, a free long-distance-by-web company, was recently sued over a netiquette fiasco. The viral campaign involved getting people to register for the service, then downloading their address books, and contacting everyone in there with the message "Register for free long distance with us, and you can talk to so-and-so who just signed up!"

Solution: Know the rules, and educate your minions

Remember the basic premise of viral marketing: You are motivating your users to evangelise for you by offering something positive. "Motivation" does not mean force, threats, dishonesty or stealth.

Remember the basic rule of business: Build a customer base through good service, good products and trust. Whatever tactics you try, don't violate the trust of customers you've already won over.

When you evaluate a viral campaign, ask yourself if it violates these basic tenets, or if it asks the participants to violate them. Is the prize so large that it motivates false entries and spamming? Is the tactic so aggressive that you will saturate the message? Is it gaining new customers in such a way or at such a rate that you will alienate your previous customers?

Problem: Too much of a good thing

Viral tactics are designed to grow exponentially. It's so easy to click "Forward", add 10 addresses, and hit "Send". When you are dealing with Web promotions, the action might involve the respondents hitting your website, registering, downloading a large file, requesting a freebie or buying something.

Is your Web server ready for a 10- or 100-fold increase in traffic within a day? Is your response staff ready? Is your budget ready?

Solution: Keep the spread of the virus properly valued, paced and targeted

Target, target, target. Again, viral marketing works best as a community-based event. Visitors should be spreading the word to friends who will be interested in the topic, not to everyone in the world.

The reward should be relevant to the market you are targeting. The reward shouldn't be so large that it motivates cheating or over-spread. The reward should have your message or brand all over it, so that everybody knows this is about you.