or website. The detailing fanatics likely could give you a 100 step process, but the big three are.

1. Get the car very clean before starting, because any grit on the surface is going to get ground in.

2. Use plenty of lubricant and light pressure moving in consistantly in the same direction.

3. If you drop the bar on the ground, throw it out.

My understanding is that clay treatment is to shave off stuff that's stuck to the paint, and standing above the surface, like overspray, metal dust, etc.
If looks and feels smooth, it probably doesn't need it.

(Don't park in a railroad switching yard for a week like I did when my Volvo was new..)