Smoke brushes or vectors are not used these days anymore. We prefer stocks with smoke instead with a little modification. Each render has a natural light source, for example in your render you can see it on top-left of Ezio's hood. To make a light source pick a small brush with low density such as 40 to 60% maximum is 80% though. And click one time over the spot where you want the light to appear. Try to avoid using too many details or effects, stick with one pattern of effects. There is variety of effects such as smoke, fire, ice, C4Ds, vectors, and filters. Filters are your best friend while learning how to add effects, there is no specific way to learn effect, you simply must use and try everything you can get your hands on, it's a very long process, and sometimes might be dull. I'd recommend reading tutorials or watching some online tutorials on YouTube, It cuts long path short.