Wash your car but make sure you don't splash the cars of your neighbours, you won't believe how petty some people can be.
Don't let your neighbours use your tap if you are on a water meter.
Make a point of keeping your parking space clean - scrub it with a hard broom and diluted Jeyes fluid every now and again. This will stop green algae growing on it.
Try to keep things civil with the neighbours, the last thing you need is an all out war with people who can make your life a misery, but don't be bullied