Secrets to cleaning your machine?

What’s everybody’s secret? I see a lot of really clean cars that seem to have never seen mud. I wash mine with soap and water, but there is always a film of mud left in the cracks and crevices. I’ve heard of laundry detergent mixed with water in a spray bottle letting it sit for a few (not letting it dry) then wash with regular car wash soap and water. Never tried it though. Need some tips! Thanks!