I won't repeat a lot of what's been said here. It's all good advice. Slow down, test your route, watch traffic, get lots of blinky and reflective things.

One thing I did when I started planned by commute route is used aerial photos. Using Bing map "Birds Eye" view, I figured out places where I could cut through, sneak around. Overall, it saved me about 2-3 miles.

Get out, explore your route. That's the best advice. Plus, it gives you an excuse to ride more!