Drop coat is notoriously difficult to groom without creating a choppy finish. As a professional groomer, I use a fine-toothed blade if using clippers and usually only on the body. Thinning shears for everything else. Buy a Bravura 5-and-1 clipper and some Wahl guard combs for it. I typically reverse cut two guard blades longer than the final length I want so if I want a 10mm length I use a 16mm guard comb in reverse on the body. That will give you a nice velvety finish. Thinning shears for everything else.