Check your area, most local PDs only require a HS Diploma, the State Troopers require at the least a Bachelors degree. Once you find the requirements out in your area you must sign up to take either the Civil Service Examination or the Cheif's Test (depending on the area you live). Your score on that will put you on a list. Your position on that list is your chances of becoming a LEO. If you are not in the top 5% chances are you are not getting hired within the next 2 years. Your scores stay on file for 2 years at which time you have to test again. Then, even if you get a high enough score on the test, pass the interview, pass the background check, and pass the psych eval, you still have to be physically fit enough to make it through the acadamy.
I'm workin on becoming one right now
PS To take the test you have to sign up. I know in my area the sign up deadline is long gone, IDK if it is different where you live or not, but here you have to wait 2 more years until you get another chance to test. Yes you can study for it, I suggest taking the Bernstein Prepatory course for it. The offer a free 2 hour seminar every single year to get you accustomed to what they teach, and then they offer a 2 day seminar for 400 some odd dollars, but VERY well worth it if you ask me. They teach you how to answer the psych questions to get the highest scores, they teach you tips and tricks for how to read more critically and other things of the like, there is also a study guide that the NJDOP (Department of Personnel) actually publishes, definatly a recommended read!