Social technologies for educators are useful for communicating and connecting, curating and sharing resources, and networking e.g. PLNs.
Things to think about include using lists rather than following people, the careful placing of images/photos, which stay on profiles, passwords and account access which may be on mobile devices, reputation and impact of tweets, moderation and engagement.
Hashtags should be specific, short and memorable. Don't just RT, ask good questions - not things that could be easily searched for; ask things about others. Think about structure, information and hashtags and don't worry about missing things.
http://goo.gl/ is an URL shortener. It gives a lot of statistical information as well as shortening URLs. This is useful when composing tweets. All shortened URLs are publicly available.
When tweeting about an event, include details of location, date etc.