For me the best way to work with smoke is so called smoke grenades - little cylinders with a thread, when you full the thread they generate intense, bright colored smoke for about a minute. This is what I learned about using them for a fashion shoot:
- Some models freak out - they are afraid to pull the thread too strongly and break the grenade or that it is going to explode in their hand. In this case I just activate the grenade myself and then pass it to my model.
- Sensitivity - some girls are more sensitive to the smoke than others. I can stand in the smoke and breathe it and I feel ok, but for one of the models, she started coughing and her eyes got watery from smoke exposure, so I asked the MUA to hold the smoke grenade either behind the model or between the model and my camera
- Residue - smoke doesn't leave residue on the ground, but it once left a stain on model's t-shirt when she directed the grenade onto the fabric, so if you are doing fashion editorial or borrowing clothes be careful where you point the grenade
- Volume - I used 2 different brands, one gave bigger volume and kept it up for longer 90 vs 60 seconds. For the reviews I got that people think the bigger smoke cloud the better, but for me actually smaller grenade worked best - smoke was more transparent, I could shoot through it much better than with bigger grenade and also as the cloud was smaller we drew less attention with it
- Movement - make sure to let the model or assassinate direct the smoke and sort of draw with it - you can draw a snake or a circle, use smoke to show model's trajectory in the frame. At the same time don't hesitate to hold the smoke still and use it just like mist on background or foreground
- Light - try directed light to show the texture of the smoke as well as soft ambient light to make an accent on color and contra light to light up the whole cloud
- Restrictions - don't use the smoke in a city or industrial area, don't direct the grande to model's face, be ware that sparkles can appear when activating the grenade, don't plan to transport grenade on a plane and dispose used grenades with extra care.
Good luck ;)