keep it concise as possible; if you don't have too much to say, then don't BS to make your resume longer. Besides, from the point of view of a recruiter who must read through everyone's resumes, the more concise a resume is, the better, because that means a) less paper to handle, and b) less crap to read through to figure out what you actually did during your job/internship.
First, you need to alter your resume based on the type of job you are applying for. If you're a bio major applying for a research position, it might be a good idea to list the classes you've taken that are relevant to the position. This not only shows the recruiter that you're a viable candidate based on experience, but also that you've done your research on the position. Play up any past, similar experience you've had with the type of position you're applying for, and emphasize skills that you think might be necessary at the job.
Read through your resume carefully and delete anything that is repetitive. If you learned one skill at a job, don't list it again later somewhere else. If you're very serious about resume pruning, http://lifehacker.com/5137212/six-words-you-should-drop-from-your-resume and http:// hotjobs.yahoo.com/career-experts-10_boilerplate_phrases_that_kill_resumes-97 are really good articles to read.
Then, beyond just the content of your resume, you have to make sure the presentation stands out as well. I personally prefer a very clean and minimalistic look to resumes, because important elements of your resume are easier to find. http:// ceevee. com / is a good web utility that helps you build your resume, and the end product is very simple, but effective.
sorry for the links above, because of discuss campus's restrictions on the numbers of links per post, i had to insert random spaces into the links x.x
yuppp hopefully this helps!