Almost all of the open competitive tests for almost all civil service positions are going to be common sense, reading comprehension and basic intelligence. You do not need any special knowledge for the police officer, fireman, sanitation, conductor or train operator. The respective agencies will assume you know nothing at all about the position you are applying for. They will train you for that particular job in their own way. The civil service test shows them that you possess the ability to absorb and learn the job once they hire you. I have taken many various exams over the years and have found that I got better each time that I took them. I would suggest taking the police exam and fireman exam for the experience, even if you are not at all that interested in those jobs. Someone in a previous post suggested that you join the military in the meantime. Do 4 years in the army ,navy, air force ,marines etc and you will gain great benefits in experience. If a civil service exam pops up while you are doing your enlistment sometimes you can take leave and come back, take the exam and perhaps have a job waiting for you when your enlistment is up. Just making a suggestion . An honorable discharge is something that almost all employers look very favorably on..Good luck to you Jay.