Depending on the type and formula of lavender-hued product you use, the application process can differ.

“If it is a cream or liquid product, I would ensure that a thin, even layer is applied. The hue shouldn’t be as visible once applied on the skin as it should cancel out the desired tones once blended,” Cintron explained, adding that for powder products, it’s best to apply using a powder puff then dust off any excess after the desired brightness is achieved. 

Cintron doesn’t recommend lavender tones for deeper complexions, as they can make skin appear ashy and unnatural. Instead, people with darker skin tones might see a brightening effect from orange- or red-hued color correctors. 

Source: https://www.buzzfeed.com/tessaflores/this-might-be-the-best-kept-secret-for-brightening-your