Hi Charlie,
Here is my 2 cents (I didn't include any links out because you can get those on the blog post, didn't feel like duplicating the work...)
The basics
Create a professional twitter page (and if you have an interesting background, submit it to Twitter background).
Download an application like Tweet Deck. It will allow you to tweet from your desktop and to better organize tweets, track who responded, who retweeted you, etc.
Set up your blog to create automated tweets each time you post with Twitterfeed.
Start with connecting to people who are big twitterers in your industry. Starting conversations with them will get you noticed by their followers. Make sure that the conversations are valuable, interesting or entertaining. If you're not sure who to follow, use a service like Mr. Tweet.
If your business is local, find local people to follow. A great service to find local tweeters is Loca Follow.
If people retweet your post, thank them. Automatically follow them after 3 retweets. That is called twitequette and will increase your likeability on twitter. Don't forget that to get you have to give.
Periodically search for mentions of your company by doing a twitter search. Start conversations with the people that retweet you.
Retweet interesting tweets from others, promote them and they will promote you.
Tweet interesting links and tweets.
If you can, be funny.
Tweet during peak hours.
Making it viral
Make your tweet virus worthy. Don't write this tweet: "How to write interesting tweets" but write "How to write magnetic tweets that can get you 1000's of followers". The second tweet has energy and mentions a desire that most twitter users share: increasing their followers. If you can make it less cheesy, be my guest, but this stuff does work.
Use twitter to expose your ideas to those twitter users who need it or would appreciate it. Tweet it to them, and if they start a conversation, engage.
Give your promoters a way to easily tweet your idea or blog post. Add a tweetmeme button to your post for instance.
Try to create virus worthy ideas or blog posts that build up and spread over multiple days. Make it as interactive as possible, allow users to comment, vote or do something else. Make it communication worthy.
Keep relationships with those people that actively engaged and engage them for future virus worthy ideas.
Twitter for business
Search for "I need *product*" or "my *product* sucks". Replace *product* with what you offer of course.
Research the twitter followers of your competitors and start relationships with them.
http://onlinedesignbureau.com/blogs/marketing-blog