Ok not sure I'll come up with ten but I'll just rattle off some things I do/plan to do with mine. Some of this will be applicable to any car and some specific. Not necessarily in any order and I'm sure there'll be stuff I forget but here goes:
- Keep it clean! I'm a bit more obsessive about cleaning being one of those that frequents the detailing section regularly but there is method behind our madness! When a car is clean and particularly if you wash it yourself, it's much easier to spot any damage. Things you may not notice if dirty such as a new stone chip or cracked headlight lens, whatever. If you look over the car regularly then you'll notice these things and can easily touch up a chip for example that may cause rust problems further down the line! And you'll have a nice gleaming motor as an added bonus

- I know this is only applicable to some GTIs and is in the service schedule, but if you're a DSG owner, make sure it's serviced on time! This seems to be key to preventing DSG problems and I think it's a fixed price service at around £170-180 every 40,000 miles. Imo not a lot of money for the piece of mind, especially considering the repair bills that go along with DSG problems.
- There's been much said already about the timing chain problems on the 2.0TSI engine so if you dont know what this then have a look here:
http://www.golfgtiforum.co.uk/index.php?topic=262793.0 . As far as I'm aware there isn't a specified interval to change the timing chains/tensioner but even though mine is a 2011 car and it appears only to be 09-10 cars that are affected, I shall be carrying out preventative maintenance regarding this. At 80k I plan to have the tensioner, chains and all guides replaced as a precaution. Will also be changing the water pump at the same time as well, as there is documented issues with these failing and leaking. Not sure on the cost of this yet, but I don't fancy the cost of a replacement engine if the tensioner does fail.
- Applies to all cars but let it warm up and cool down. I always have my DIS set to display oil temp and then keep revs under 3000rpm until the oil has hit 70C. Likewise at the end of a drive I like to let the car idle for 30-40 secs just to let the oil and turbo cool. Turbo life is the key reason here.
I don't want to patronise or teach anyone to suck eggs but I assume you are already checking tyre pressure, oil level, bulbs etc regularly?