Depends on your age but there are several things you can do. Start by take some college courses. Here on the West Coast, most local agencies do not require a degree; however, many federal agencies, including the FBI require a four year degree just to get your foot in the door. If you do take the degree route, I suggest a degree in something OTHER than Criminal Justice or the Administration of Justice. The reason is this: Local agencies will send you to an academy and teach you how to be an officer hence a Criminal or Administration of Justice degree is not really necessary. But if you get a degree in say Business or Law, you can use it for careers other than law enforcement should it not work out for you or you are disabled on the job, etc.
Another route is join the military. Military service is VERY attractive to law enforcement agencies and will even help pay for college. Having served not only demonstrates courage, but teamwork, discipline and commitment. It will also give you the chance to mature through new experiences.
Finally, become a Reserve Police Officer. This will expose you to police work to see if it is really for you or not. It will also make you very marketable for a full time position in the law enforcement field, for reasons noted under military service.
My final piece of advice: Take any kind of writing and communications courses. Having been a training officer, I can tell you report writing is very high on the list of reasons trainees wash out. English, spelling and grammar are critical in our field.
Hope this helps Ruby, and good luck!