2 bucket method,
2 buckets with grit guards in both, 1 bucket with your soapy water and the other with plain water, dip washmitt in soapy bucket,wash a panel gently then dip washmitt in plain water to remove crap from it then dip back into soapy bucket and repeat the process till cars fully washed, it minimalises you spreading the dirt/grit etc all over the car and inflicting scratches and swirls.