It is not my intention to dissuade you from looking for job postings on websites or newspapers. I am not advising you to never use a placement/staffing company. These are additional avenues for your job search.
In fact, use all of them. Remember: Reach and frequency. Your objective is to get your name and experience in front of as many people in as short a time as possible.
What I am advocating is that you take control over all these avenues. Do not be passive in your search and in the marketing of your skills.
Carefully read Chapter 12. A job search is an extension and compressed professional networking opportunity.
It is likely that the best job opportunities you come across will be when you are gainfully employed. To ensure that you are ready and can properly evaluate such opportunities, make sure your toolkit is up to date and that you are networking as you go, not only when you need to. This is the proactive approach to career development in general and to the job search in particular.