I find the clock code method the easiest:
Think of the face of a clock divided into portions of 1 hr -
0 degrees = 0 crosswind (of course)
15 degrees (15 mins) = a quarter
30 degrees (30 mins) = half
45 degrees (45 mins) = 3 quarters
60 degrees (60 mins) = full.
An easy rule of thumb and if you look at 18 greens' sin table it is pretty accurate and any error is on the side of caution.