One traditional way is the "Manual Air Plot", but you really need another pair of hands (or a Nav!).
Thusly: you plot your heading and TAS on a map, completely ignoring the effects of wind. The theory then says that after a given amount of time (Ideally an hour or easy fraction thereof) you plot the difference between your actual position and the Air Plot position. The difference will be the wind effect.
Which all proves that "Directional Consultants" entire raison d'être depends upon the effects of wind.......