I'll disagree with some of what he said,
Direction DOES make a differance.
If the clay is picking up ANYTHING those things will leave super fine scratches.
When I clay, wash and shammy dry I always go in one direction. Same direction each and every time.
Front to back on the hood, left to right on the sides and rear.
Also I use more lube than a spray. I wash with dawn than create a new clean bucket also with dawn and use that as a lube. Then I wash again with a third new bucket of dawn. I use Meguars car soap for all subsiquent washes however. I only use dawn if I am claying and applying fresh coats of Zaino.