Just add 1 to 2 ounces of auto shampoo to a 16 ounce spray bottle and shake well. Apply liberally to the surface and clay.
When complete with the panel, rinse off with a hose or wipe with a cloth.
Some detailers do clay while they wash, and then rewash that panel after claying.
Most of us usually wash our vehice after claying and before polishing to get any residual soap and clay off before we start applying any product.
If your paint is in excellent condition, you can go right to your sealants, but most of us like to polish if we find any defects or stains in our paint.
Remember, a great finish is 90% preparation and then 10% wax or sealants. Prep the finish right, the rest is gravy! Enjoy!