I always use straight white lines, and as they progress, I make them curl up at the end and disappear.
A quick Google revealed a possible example of this technique - see the line in the top right corner of
this clip.
Naturally, as well as leaves and debris, also show the effect of the wind on anything fixed in place that it can affect (bushes, trees, clothes on people or on clotheslines, hair, flags, etc.), and sometimes on things it really can't affect (buildings, etc - hey, this is a cartoon environment, make that building sway like a tree in a strong wind).
Try and add in things that can be affected this way.
Here's a clip that might be worth watching.
Regards, Myles.