Looking for job is not easy especially that there are a lot of people nowadays who are not employed and the competition is quite tough among applicants. If you are serious about job hunting you need to plan it. Sometimes it took months before one can get job, so you really have to make careful planning. Proper preparation should be done primarily with your curriculum vitae or CV. CV is the window of your employer to you, your knowledge and skills. A badly prepared CV will reflect and might be the reason for the not being listed.
Persistence is important since you may have many applicants but may not be a successful one. Do not be discouraged when you are not called for interview. Make sure that the position you are applying is fit to your qualifications. Because you may end up hitting the wrong target.
Make the best effort the pass the interview.