How would people usually create smoke? So I need to create smoke because I'm doing a render of a crashing plane. What I was wondering is that do people only simulate smoke or do they sometimes model it? I've seen people do both but I was wondering which way works well.

Thanks!

NOTE: I'm not sure if it changes anything but I use cycles.
It depends. 

By manually creating the smoke you have as much control as you like, but it will take more time (at least more of your time. Smoke sims can take awhile)

For more realistic results, animations, or less manual work, the simulator sounds like the way to go.

I'd recommend trying to simulate it first, then moving to alternate methods if you are not satisfied.