It just takes time. But like what has already been said go for a walk or take a drive (great while on duty...kills time and the company pays for the fuel! ) One of the major things that helps me was my stint dispatching; believe it or not.
I work for a private company that runs several different divisions and I work in two of them, so I've had to learn two different cities/counties. In the one town everything is split up north/south by Broadway and east/west by the railroad tracks. Just take something basic like that and expand on it. The other city the main drags are numbered running north and south but they start numerically east to west.
Just whatever helps you out. Look for landmarks and associate to those. That also has helped me out alot. Being able to say that's right next to this or that church or it's by McDonald's etc is helpful. Hope this helps you out. Good luck!
Pat
