Building and maintaining trust and credibility with your followers is essential for successful marketing on Twitter.  You don’t need to take my word for it.  Here is another opinion.

When you are ready to make money with Twitter, don’t blatantly promote your products or services. Some people could think that you are trying to spam them. It’s not a good idea to mention your product to your followers every time you send a tweet.

Source = http://semways.com/archives/86

Your followers need to percieve value in your tweets if you want them to continue to follow.  For advanced twitter methods, check out Twitter Treasure Chest.

Related posts:

1. Are Your Twitter Tweets Retweetable?
2. Twitter Marketing Secrets – How to Turn Twitter Into a Goldmine For Your Business
3. Using Clickbank And Twitter Together
4. Twitter Tools to Help You Manage Your Following
5. What Is Twitter And How Does It Work – Good For Marketers?