The drying out of lines, etc. is a lesser evil than the varnish deposits left on the carbs after an extended storage. Especially unleaded fuels (don't know about diesel though), which destabilize in a period of weeks.
I once stored my Bug in a warehouse temporarily until I could get settled in another town I lived in. Well months became years, and it was at least five before I was able to get back to the car. It took months to get the car back in shape!
The carbs had to be rebuilt due to the deposits left from storage, the batteries were dead, several wires in the harness had corroded so they had to be cleaned, the tires replaced, the brakes and drums replaced, the oil pressure gauge lines replaced. I didn't have mice eating anything, but they probably would have done less damage!!! And this was a SHOW car, not a driver!!!
The car never was right since the storage, so one day I will have to rebuild it.
Six months isn't a lot of time for deterioration, so most of the tips already posted will be just fine. But cars are meant to be driven, not sitting, so unless you go through extreme measures for long-term storage, you are doing more harm than good by letting it just sit there.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car