Twitter usage - how to be more professional

I've recently written an article giving some top tips for Twitter users. You can view the article here:
http://www.freshbusinessthinking.com/business_advice.php?AID=8590&Title=Top+Tips+On+Tweeting

Its quite surprising for me to see so many regular users of Twitter still doing some pretty basic or incorrect stuff and not making the most of their precious 140 characters. There's some obvious question to ask, for example:

• Why don't people shorten their URL's to make the most effective use of their posts (and to measure click throughs)
• Why are hashtags not used more regularly?
• Why aren't more posts repeated if they are important?
• Why do so many postings still have spelling mistakes in them?

Just because Twitter is an informal social media channel, it doesn't have to be used unprofessionally.