Black, lots of good advice here already. I give you this from my perspective who worked with many officers, deputies, troopers, agents, etc., et al as as ex-deputy prosecuting attorney. Please understand that I tell you this as someone observing from a far, the current and former officers can tell you much, much more and as a pogue I intend no offense:
1. learn the English language, in both written and oral forms. Being able to communicate will save you trouble on the street and time away from depositions and trials;
2. learn Spanish, immigration trends will continue for the next couple of decades. Learning Spanish will help you professionally;
3. learn to wrestle and to fight on the ground. Of the thousands of police reports I read, when there was a fight, pushing match, or a crack dealer running from the po-po, it went to the ground. I have and do study several martial arts, mainly forms of Chinese boxing; however, in police work you have to be close to people to arrest them or separate people. Fights usually take place at "ramming speed";
4. Find an activity that you can stick with to stay in shape. Here, oddly [
] it is basketball (euchre at lunch does not count). The agencies in my county have intramural teams that play one another. IMHO, martial arts are great for this--Hapkido, forms of karate, jujitsu, boxing, etc. As a LEO I attempted to teach boxing and shooting to my fellows if so interested;
5. Find an strong, understanding woman. As you can imagine the life of the police officer is devasting to partners who do not understand going in what the life is like. Just dealing with prosecutors (court delays, witless conferences, trials) is enough to make most spouses cry.
Find a strong woman who understands what police life is like. This is vital for all walks of life--a good partner will help you more than anything else you do;
6. Make friends outside your line of work--gun clubs, Kiwanis/Lions or church/temple/mosque are excellent for this. LEOs hang out with other LEOs and like "worms in a jar" (no offense, phrase of Uncle Jeff's) feed off the vibe given out by others;
7. Lastly, make sure that this is want you want to do. If not, do something else. If you get into the job and hate it, you will be unhappy and others could be hurt because of your internalize anger at your job choice.
That's what I know from my years dealing with "line officers." I never walked in their shoes, I never endured the frustration and boredom of a 10pm-6am Tuesday night in February shift. Take it for what that is worth.