Misdemeanor marijuana is not a huge offense-- but it's still a criminal offense. Considering that you are a college student, you are pretty young to start racking up a criminal history. Before you enter a plea, you need to see what affect it will have on your college status. Some universities have very strict rules regarding the reporting of charges or convictions. Others can deny scholarships based on misdemeanor convictions. Normally, a misdemeanor would be a minor hiccup in a job search. But for some college students, it can mean a loss of funding which is a huge issue in this economy..... so really take the time to know your college's rules.(look at the website, handbooks, by-laws, codes of conduct, etc.) Also review your potential career choices and see if it will have an impact on that choice as well. Some medical professions do not authorize a license for those convicted of a drug offense. How you plead really depends on the evidence against you and your future objectives.
Because this is your first offense and you are so young, consider visiting with a criminal defense attorney in your area for any diverison programs (informal probations that do not result in a conviction) This could help you resolve the case without the ding of a criminal conviction. If you're not guilty of the charge, they can help you develop the evidence to defeat the charge.