Maximize your profile. You can set up a resume online and use the website field on your profile to link to your job history or a LinkedIn page. Make sure that your name and username are professional, preferably some variation of your real name. (i.e. JohnSmith, JSmith, etc.) You can put your objective or information about what kind of job you are looking for in your bio field. You may want to keep a separate profile for personal use. Also, use a professional photo in your bio as your image.
Follow the companies in your desired industry and other people in that field. Stay in the loop regarding the businesses that you hope to work for. Keeping up with industry news is easy with Twitter, so find the people who are posting in your field and follow them. Make use of these connections and send direct messages or @replies that will give you some credibility. Retweet relevant information and build relationships.
One Twitter tool that you can use to help with your job search is TweetMyJobs. This application has been featured by Forbes, Business Week, and other news sources like CNN because of the sizable number of jobs available on the many channels. The listings are broken up by industry, region, and job type.
Boost your credibility with your tweets. Let employers know exactly what you know about your field. Link to quality information and make intelligent @replies and RTs. You shouldn't pretend to be someone you are not, but present yourself as knowledgeable and as experienced as you are. Be creative with your posts, but be relevant at the same time.
Another Twitter tool that may help you is Twellow. This application allows you to quickly search through member profiles and tweets by typing in company names, keywords, or the names of people. It is the yellow pages of Twitter. Once you find relevant profiles, you can connect.
Use hashtags. The formula for hashtags is simple: #keyword. For example, if you are looking for a job in education you might tweet with the hashtag #education, or #teaching. This will increase the chances that employers will find your tweets in a search. If you need ideas for relevant hashtags, try Tagalus. Type in your keyword and it will suggest related keywords.
Don't aggressively follow every prospective employer or individual related to your field. Be selective about who you are affiliating yourself with and don't add 20 follows in a single day. Pace yourself and build your connections gradually. You do not want to develop a reputation as a spammer.
Make use of these tips and Twitter tools in your job search. The technology is there to help you find employment opportunities and you should take advantage of it. Good luck finding work!