I sporadically use twitter- when I have the time, I love browsing through it, when I'm busy, it's relegated a back-seat. Twitter however can be a powerful tool, not just to make friends and online contacts, but also to keep abreast with what's happening in the market, sell you products and services and gain new clients.
Because of the limited number of words you can use each tweet, try and keep in mind the following:
Your headline should be interesting. Funny too is good. Most people will retweet your tweets without actually clicking on the link, if your headline captures interest.
If you promise something, always be sure to deliver.
Ensure readers understand the urgency of action- Buy Now, Last Day Offer, Click Now- are all great ways to get readers to click on the link.
Stick to one topic. Tweeting on your restroom activities and what your dog ate is really of no interest to people. A well written article which offers advice, is.
Avoid blatant selling. I have to say I sometimes indulge in it, but it's never got me any hard core fans, just those who want to gain more followers. Keep promoting your work subtly and you'll find it a better way to capture audience interest.