What are your very best tips for marketing on Twitter?

I am hoping to gain some additional insight here from people who enjoy answer questions. I will add each of you that takes the time to answer and thank you on my Twitter stream.
@dannyarrington

Hi Danny-
Here are my best tips:
1) Do not be too "salesy". Be conversational and occasionally you can work in something promotional.
2) Mix business with personal. No one wants to hear about business all of the time.
3) Regularly post to Twitter – at least once a day.
4) On the flip side, don’t post too much. No more than 1-2 hour or you will annoy people.
5) Provide good information (articles, tips, advice) so people will want to follow you.
6) Be engaging – answer questions, ask questions, respond to people
7) Be polite – thank people when they retweet you or recommend you as someone to follow.
Help promote others – retweet valuable information, call out your favorite Twitterers by their Twitter name.

Hope that helps!
Lyn Mettler
Step Ahead Inc.
@WebPRGirl