For the oil and temp, it's just a matter of preventative maintenance, and being paranoid.
Check the oil every time you fill up. And run it an extra liter over. There's plenty of room in the pan for an extra liter. Run good oil - I use Castrol Synthetic 0w30, but there are plenty of good ones out there - and change the filter every 5000 miles.
Same kind of deal with the temperature. Make sure there isn't junk between your AC condenser and your radiator. Make sure you have a fan shroud, and verify that your fan and fan clutch are in good shape. Replace the rubber coolant hoses - especially the smaller 90 degree ones below the cam position sensor and at the rear exhaust side of the block. And if you drive the pre-89, the rubber plug near the rear 90 degree hose should also be replaced. Replace your radiator cap, and the lines to your overflow tank, including the pickup line in the tank itself. Buy an aftermarket temp gauge - with a warning light!
There's nothing complicated or revolutionary here. It's all 'common sense' - but that seems to be remarkably uncommon.