You've mastered the basics: You've maximized your provider profile by listing your skills, posting a portrait, taking all the relevant skills tests, and filling your portfolio with your finest work. You're applying for jobs, but maybe you're spending more time applying than you are interviewing. Maybe you'd like to lower the ratio between jobs you apply for and jobs you get. Maybe you'd like to minimize the occasional bad relationship--the buyer who changes terms, makes unreasonable demands, turns out to have no communications skills whatsoever. Job postings on oDesk aren't like a newspaper classified or on some sketchy job board--there's a lot more data that can help you spot serious buyers, figure out where to focus your resources, and to enjoy the work that you get.
What is the job? Carefully read the job description and what's between the lines: is it well thought out and thorough? Do I believe that the buyer is a good communicator? Will she clearly outline tasks? Does the buyer come across as professional and will not "leave me hanging"? Is the job in an industry that is rife with fraud (e.g. porn or gambling?). If it's in such an industry, can I find the company name and website?
Who are those people? Scope out the competition--who has already applied? If the buyer has been initiating contacts, those providers may have the inside track. Either way, check out the skills, feedback and pay rate of your competition. If you don't think your profile stands comfortably against those who have already applied, you might prioritize responding to postings where you'll be better positioned.
Who gets the job? On past listings with multiple candidates, did the buyer go with the cheapest or the most qualified? For the new listing, which of those would you be?
Amount agreed vs. amount paid: If the buyer routinely pays out more than the up-front estimate, this may mean she pays bonuses or raises. It may also mean she routinely fails to understand the complexity of a project. If you're already tight on time, you'll definitely want to determine which it is during the interview.
Timing: When a past job was estimated to take a week, but the hired provider took a month, that might have been the provider's fault. If you notice this consistently across this buyer's back listings, it's probably the fault of an overtaxed or under-communicative buyer. This doesn't mean you don't want the job; just know what kind of situation you're likely to face.
Applying to every job within your skill range becomes a job in itself. The amount of time you spend looking for work is overhead--it's a resource going out, rather than money coming in. Using oDesk's transparency can help you spend less time applying and more time earning money.