Tailor both the resume and cover letter. How many times have you heard people say they customize their cover letter, but send the same resume to everyone? Usually they are very proud of themselves for doing this, as many job seekers send one form letter and resume to everyone. Unfortunately, when a resume is competing with 200 to 400 others, it has to stand out from the crowd. Recruiters don't have time to separate the "diamonds from the dirt" in the 10 to 60 seconds they spend skimming for relevant experience. It is the candidate's responsibility to sort the valuable stuff from the extraneous, using only 20-carat material to land an interview.

People can be unreliable and disloyal; possessions can lose their value; jobs that once stimulated you can become boring. But principles remain steady through it all.
Nido Qubein

A resume is an important tool, but it can't get you a job. Only people can do that. If you want your job search to be successful, concentrate on people and prepare your resume to suit their needs.