On my Clipmasters for tensioning, I’d start them loose, turn the knob until I felt resistance then a quarter turn past that. It seemed to work well.
Spotlessly clean horse is the prime trick. Sharp blades and a fresh drive assembly if you’re using Andis AG line clippers. Every set I have, I’ve taken the little plastic bit off that sits below the blade as it always seems to fill up with hair.
I got caught having to wet clip once as owner gave the horse bath… three days before I was scheduled to clip. He had gotten so sweaty and grungy he needed another bath when I started. I used the E3 Argan Oil shampoo, and the blades went through his heavy damp coat like butter.
My blade cleaning routine is to blow the hair out with canned air (for electronics), dip the teeth of the blade into the Andis blue dip, tip the blades up while running to let the lube drain into the blades, then wipe the excess off on a towel I’ve got tucked in a pocket. The canned air has the added benefit of cooling the blades.
I would try the Shapley’s light oil trick if I picked up clipping again.