Take lot's of notes, never ever stick a nodoze pill in your speedloader during an inspection, always keep your weapon clean, dentist tools work great, when they tell you to keep your baton over your head while running laps, they [b]MEAN[/b] over your head. Never show up late for class if your a off-campus recruit, buy a library card at your local Law Library, you'll need it. Don't get stupid during the academy and try to be a cop that you aren't yet, take your spouse/girlfriend with you to the orientation so she'll get a good idea of what's coming for the next 6 months. Become close to your classmates and learn from them, their's always someone who excels at something you don't, did I say take notes? Keep a journal during your training, you'll get a kick out of it once you get along in years. Pay attention during officer safety classes, learn from others mistakes in this area, you and your partners/TO's life may depend on it right out of the academy. Remember, just because you pinned on a badge doesn't make you a god, you are not immortal and you're working for the guys and gals who don't have one.
Good Luck