there are several rules for driving a diesel:
-don't wait for the engine to warm; diesel engine is getting warm very slow when it is idle
-while the engine is cold, don't drive it over 2000-2200 RPM
-after a long drive, don't stop the engine immediately, wait 2-3 minutes untilthe turbo will cool down.
-use good fuel
-don't use additives (Dura Lube or other similar "Engine treatment" substances)
-in winter, use diesel fuel that was prepared for winter
-don't drive with very low RPM. try to stay around the value for best torque (usually 2000 rpm)
-service your car regularly, with quality filters and oil.