When the term "going viral" was first invented around 2005 or so, Twitter wasn't even around. The only thing you could do to "go viral" was to make a YouTube video that did something unexpected. Well, while going viral on YouTube is still a big thing, it's hardly the only target of marketers who wish to give their brand an edge. Using Twitter for marketing to viral effect is the next big thing now.
Twitter fundamentally changes how website marketing is done. At one time, your only hope of spreading word about your website was networking, the old-fashioned way. You would write blog posts about your website, you would maybe advertise in a bit. These days, you don't put out links on a website or a blog. You put them out on a microblogging platform – Twitter to bespecific.
When people get a great link to something they like, they will usually pass it around – what is known as re-tweeting. Anyone who's still stuck in the old times – when you merely left links around and hoped for a bit of google-juice – is soon going to be left behind. Using Twitter for marketing is where the action is today.
Well, you don't really need to look at re-tweeting as a special action of some kind. It's a call to action like anything else. The best way to get anyone to pass your tweet along would be to merely ask them. If they accept, it can be great for you. Each person that re-tweets a message for you, is actually lending his own personal reputation to the tweet.
Anyone on the other end who receives a tweet through someone they know, right away will believe in it a lot more than they otherwise would. To simply include a request that goes "please re-tweet", is usually all it takes.
There are certain times of the week or day that people tend to be more tolerant of a request to re-tweet. The first three days of the week usually give you better chances of a re-tweet than any other. It's always good idea to pick times like this.
Research shows that people are generally more willing to re-tweet a message if the message comes to them re-tweeted already. So a good strategy to using Twitter for marketing, would be to actually start out the whole venture with people you well, first off. This should help you get off to a great start.