Each state sets its own requirements. Beyond that, each agency sets its own requirements, so long as they do not conflict with the state's requirements. So you want to start by researching the Peace officer requirements for the states you want to work in.
Although college is not required, more and more agencies require some college hours, or an associate's degree. Some agencies will hire you even if you don't have enough college, and give you time to get it done. But, if you don't follow through, you will be out of a job.
Law enforcement has become increasingly difficult. The ability to write a good detailed but concise report is important, as is the ability to think on your feet, stay calm under pressure, and relate to people of diverse backgrounds in sometimes stressful situations. The earlier you begin researching the requirements, the better off you will be!
In the meantime, understand that when they do your background check, they will talk to your family, friends, teachers, neighbors, ex-girlfriends, etc. You want to be known as a good person, level-headed. One who keeps their commitments, pays their bills, doesn't start fights, etc etc etc. Keep this in mind as you go about your day to day business. Also be mindful of what you post on social media.
Best of luck!