Then spend some time researching the company. No matter what it is you want to do. After all, the applicant who knows more, generally wins. That would be second.
Then work on your own elevator pitch. This is the first 60 seconds of the interview. Make this crisp, engaging, with nothing left to chance. You have t-h-i-s amount of time to get on the right track so it is this important. Third.
Then work on your no-kidding, perfect cover letter. This is not a copy either, the winning cover letter is concise, but relates how you think you can help them. It will say more about you than your resume. Fourth.
Only then would I allow you to work on your resume. HR will spend an average of 20 seconds on it, yet you struggle, have your friends review it, and obsess over it. The key is to do one so you can change it easily for each job you want. That would be fifth.