Live Tweeting can be great for your business. If you do it correctly, it can get you on the map with people who may not have seen your Twitter account otherwise. Live tweeting is a vehicle to establish and maintain your brand as the source in your field. It probably will not yeild direct sales, but will expose your brand to new people interested in what you sell.
Live tweeting is when you are at an event where people are talking, or noteworthy actions are happening around you. It can be done at a panel, during a TV show, at a sports event, or any event where other people are interested in what is happening there. It is a very fast way of writing (with your thumbs or pointer fingers, no less!), since you are basically quoting people on the fly, and then hearing another quote and tweeting that. You've got to be sharp, and able to listen and write at the same time. If you can do this, you'll come away with a lot of great content to utilize in your online space, such as your website, blog, Facebook business page, etc.
Listed here are best practices, to help you look good and get ReTweeted, the coveted RT.
Include the # (hash tag) in each tweet. This is the most important move to make when live tweeting. The # hash tag is a way Twitter identifies a single subject. Whatever combination of letters that is left after a # hash tag, Twitter turns into a link for you. If everyone is talking about the same thing, the # hash tag is Twitter's way to identify that. It's like the telephone line that connects everything. Without it, everyone is talking into space and followers might not know what they are referring to, or if they are contributing at a special event.
Make your tweet easy to ReTweet (RT). This means, make them short, maybe 70-100 characters. This lets people add your twitter name to their RT, and any editorial they can squeeze in. People like to RT important statements to their own followers. Just because you said it, doesn't mean the rest of the trees in the forest heard it. ReTweets let your statement reach other audiences that you don't have access to yet (and admit it, makes you feel smart).
Credit the speaker. If you're at a panel and you hear a speaker make a great comment that you want to RT, include their twitter handle in your tweet. If you don't have time to find out their Twitter handle, then just use their name without using the @ symbol. This gives credit to your statement, rather than you stating something profound that you wouldn't have known otherwise. It can make the statement more believable.