1. For best results, you need to treat your Twitter followers like you would your list. Don't just sell, sell, sell. Give too. Give freebies, link to informational blog entries, then sell every once and a while.
2. Don't just blindly follow and hope for follow backs. Find people in your niche, follow them, then direct message them inviting them to follow you back.
3. Tweet, re-tweet, and direct message. Twitter is a community. Be active for best results. Take time to tweet. Re-tweet interesting tweets you see. (One of the reasons you should follow people in your niche. Answer direct messages and let people know you appreciate them.
4. Fill out your profile and add a background. People on Twitter don't want to follow a salesperson, they want to follow a person. Someone that is real and will share interesting or funny things with them. They want to follow people that will make them think or laugh.
5. Don't just use automated software. Sure, planning out tweets with a software is fine, it will help maintain consistency, but take some time to manually get in there and nurture your relationship with your followers.
Remember, people go to Twitter to relax, stay connected, and have fun. Keep that in mind when you are using Twitter for marketing, it takes a special touch to make sure people don't feel like you are just there to sell to them.
Any other tips for using Twitter as part of your marketing plan?