Keep your arm still and move just your wrist horizontally back and forth. Don’t shake it, you just want one continuous movement. It will usually take two or three times across to get as dense of a line that you like.

tbh i dont even bother with the line i just evenly coat the top if the foam with cocoa powder. i feel that the line doesnt give enough cocoa flavor to add to the drink

I don’t shake it with one hand, I drag it over while tapping the bottom with my other hand. Works every time

I pour it very carefully right above the surface. A partner at my store who recently transferred from a slower store said they used to use sleeves as guidelines until they got the hang of it.

Its not that deep