If this is new to you, don't feel bad. My hope is that you'll never have to spend enough time in the job search market so that the idea of marketing becomes too familiar. Essentially, the application process is about making the company aware of the benefit you can provide them. Whether this is your ability to organize effective teams, coordinate multiple projects, or implement systems that produce significant revenues, you must get this across in the first twenty seconds or so of your resume.
Time and time again, I see people underestimating the importance of this approach to marketing themselves. If you've read my $1M resume post, you'll know that you can't afford to skimp when it comes to this document. Marketing is the most important aspect of this document, and you need to make sure that your descriptions all lead a reader back to the singular idea of what it is you can add to a company.
Ideally, you will devote 40 hours per week-a full-time job's worth of time-to job searching, applications, and resume tailoring (yes, you'll probably have to tailor your resume to specific positions). The upside to this is that most people don't know that this is the most effective approach; that is, they know that marketing is effective, but they are not sure how to go about this-what to say. As long as what you're saying supports the main idea of what you have to offer-and you're not throwing in all the minutiae of your work-related duties-you'll find yourself in the right. Now write!