A good resume is very important, often even more than your cover letter. So your resume should leave an impression of someone who is capable of the job.
Your resume is all about a good presentation, in a matter of fact style.
It is not enough just to sum up your previous work experiences. You have to give the reader the impression that you know what you are doing, and that you took great care in presenting yourself because you really want that job and are capable of executing it.