First and Foremost is to think about your personal decisions as we lose a significant number of applicants to prior criminal violations when they were younger, especially violent or felony drug related crimes. Although this is shifting slightly, most agencies require no marijuana use for 2-3 years and no illegal narcotic use for 5 + years.
College is helpful but not required at most agencies. If you chose college before starting a career, we look for a well rounded applicant so don't stick to just Criminal Justice type degrees. We hire applicants with all types of degrees and to be honest, some of our best applicants have degrees in economics, business and management. You will be more well rounded to serve your community than if you have an AJ or CJ degree, which teach theory and most LE agencies don't apply at the level it is being taught anyway. Get a degree in something you enjoy and interests you so that you can be a lifelong learner.
Have a work history. The people that are having the toughest time getting hired and the ones who fail out of our training programs do not have any prior work experience. Whether it is paid or volunteer, you need to have people and communication skills. Working in any job or spending time volunteering in your community will help with communication. Of all the tools I have at work, my ability to communicate is the most important. Police departments also want to see a history of community involvement or service now so any time you spend serving, will put you in front of many applicants who left high school, went to college and tried to enter police work with no real work or community skills.
In regards to college itself, many agencies do not require college and those that do value college will often provide tuition assistance so don't go into thousands of dollars of debt just to get your foot in the door. While college is a great step and will make you better, keep in mind that college is very expensive these days and not all agencies require a degree. If paying for college right now is a stretch, most agencies will hire you if you are a good fit and many will help you continue your education once you are off probation.
Finally, make sure that serving people is what you really want to do. Contrary to you may hear on TV, the vast majority of the citizens do support their police and they expect you to provide a service in a professional manner. You can't fake having a servants heart over time so make sure that you can commit to that standard long term.