The two-bucket method
The two-bucket method
The two-bucket method is generally accepted as the basis for a good washing technique, along with avoiding using a sponge at all costs !
There's a great article on this here. Even though it might sound a bit silly to have a whole article on something so basic, check it out, you might learn something (I certainly did) to help keep your paintwork in good condition and to minimise adding the dreaded "swirl marks".