I favour wind up when calculating hdg & GS from a given track & TAS (the most common problem) as it correctly represents the vectors and no iteration is required.
I successfully got 96% in CPL flight planning using the appropriate method for the task.
The way to remember is wind up blows you to the centre dot from the wind dot - so track is under the centre dot and GS under the wind dot.
Wind-down blows you to the wind dot from the centre dot - so hdg&TAS is under the centre dot and GS&track under the wind dot.
Draw on your triangle of velocities onto the computer and all should be clear