Depending on how miles you drive I would recommend washing your car on a weekly or fortnightly basis.
Washing
Start off by rinsing your car with an open-ended hose pipe or with a pressure washer, paying particular attention to your alloys and wheel arches.
This will loosen any dirt or grit & greatly reduce the possibility of damaging your paintwork.
When it comes to washing your car I would highly recommend using a lamb's wool mitt instead of a traditional yellow sponge.
This is because a sponge has no way of lifting dirt away from the surface of the car causing any dirt particles to be dragged around the cars paintwork causing swirls & scratches.
A lamb's wool mitt however has a deep pile that allows any dirt particles to be safely drawn away from the cars surface.
Lambs wool mitts are readily available from many supermarkets & car accessory shops.
By far the best way to wash your car is to use the two bucket method.
This involves having one bucket containing your shampoo solution & another containing just clean water.
Start by soaking your mitt in the shampoo solution, wash one panel of the car then rinse your mitt thoroughly in the clean water to release any trapped dirt particles, before soaking your mitt in the shampoo solution & then washing the next panel.
Using this method will greatly reduce the risk of causing damage to your cars paintwork.
To clean your alloys & wheel arches it's best to switch to a microfiber wash mitt as these are harder wearing than the lamb's wool mitt & so are better suited to the higher levels of dirt & grit found around wheel arches.
If possible use a dedicated alloy wheel brush to remove the worst of the dirt.
Drying
If your car is left to dry naturally you will end up with unsightly water spots on the paintwork.
The best method to dry your car is to use a microfiber drying towel.
These are able to absorb large amounts of water leaving a streak free finish (& will cause less damage than a chamois leather)
The best technique with a drying towel is to pat the car dry rather than wiping the towel over the surface.
This takes very little extra time but will again minimize the chances of any damage to the paintwork.
One last point about bird droppings!
These are very harmful to a cars bodywork being highly acidic & if not removed quickly can lead to permanent etching of your paintwork.
To easily remove, soak a piece of kitchen roll in warm water, leave over the offending item for 5-10 mins then rinse off with warm water-try to avoid rubbing as this can damage your paintwork.
