Couple of comments (but Im no professional!)

Maybe start with foaming the car with a jet wash if you have one (you can get foamin guns for normal hoses if you dont). This will losen the main big dirt particles, then jet wash off as much as you can.

Wash using the two bucket method using your sheepskin mitt. Two bucket method stops you from reapplying dirt to the car each time you rinse out your mitt.

Dont use a sheepskin / lambswool mit on rough areas like arches and wheels - you'll destory it - use a microfibre one.

Maybe clay the car if needed? (probably with a light clay)

Also perhaps consider a pure sealent before waxing? Poorboys Ex-P or Ex.

Then inbetween major washes like that use a detailer (which you can also use a a lubricant for the clay) to keep it clean.