Any/all shops can do the basic service
Oil, Oil filter, fuel filter, air filter, spark plugs, coolant, brake fluid,
Then the checks - braking, suspension, tyres and pressure, lights, blinkers, wiper blades and HORN!
When you end up doing it yourself - keep records and reciepts. (Kms and consumable). This is just for when you sell it.
Oh and wash it more often dude. You didn't get it detailed to let it go again.
Major service every 100k kms - for you I'd get this one done at a Skyline specific shop.