There's no doubt that millions of people are on Twitter, including plenty of businesses. But many small firms are still unsure about the value of Twitter.

The current debate on the Marketing Donut forum reveals that while there are some ardent Twitter fans in the business world, many other entrepreneurs are still asking how Twitter can help them.

Marketing Donut expert, Mark White, runs Better Business Blogging, offering e-marketing and blogging services to SMEs and corporates. Twitter, he says, can be a powerful way for businesses to forge relationships but it must be used with caution.

?Twitter is an excellent social-media based route to highlight and ultimately promote yourself and what you do,? says White. However, you shouldn't sell on Twitter, he cautions, it is about relationship building.

So what are the advantages of being on Twitter for an SME? ?As your followers grow, it's an increasingly attractive way to drive additional traffic to a blog or website by highlighting new posts or information,? he says.

Social networking sites are also a good way to ?extend your network by connecting and conversing with new people, especially those in your industry. Another positive is that you can often find and link to potential business partners.?

If you operate in a specific sector, Twitter can be a great way to keep up with developments and make new contacts. ?You can receive a continual stream of content, ideas, links and resources relating to your area of interest or expertise,? says White. ?It's a great way to find information and to pass it on as well. You can also get feedback or instant research for your own projects or proposed services.?

Indeed, if you're an expert in your field, Twitter can be a good way to answer people's queries, share information and demonstrate your own knowledge.

However, despite these opportunities, White does sound a word of caution. Twitter is a commitment, he says. ?Starting and then leaving your Twitter account can give the same negative impression as an out of date blog. So plan what you want to use it for and stick with it or else you will find that it peters out.?

So what should small firms talk about on Twitter? ?There's really no ?wrong? way to use Twitter,? says White. ?If people don't like what they read then they can opt out or unsubscribe in an instant.?

A good rule of thumb, however, is not to simply talk about yourself. ?It's easy to fall into using just one type of Tweet ? always about yourself, always re-tweeting other articles or always linking to your blog posts. Don't just try to sell with it ? you can promote to your followers but if that's all you try to do they will switch off.?