just keep in mind good locking practices, don't leave your bike in some dark corner, find somewhere that's open and well trafficked, in other words, where someone will notice if someone starts taking bolt cutters to your bike.

Any locking method can be beaten given enough time/research/effort, D-locks are heavy but as long as you get a properly keyed one they are good, but then again, only as good as how you use them. Clamping your front wheel to a wheel rack only stops them running off with your front wheel.