While performing an eyelash perming service, which factor should Qing consider when selecting the size of the eyelash lift shield?

When selecting the size of the eyelash lift shield, it is essential to ensure that most of the client's lashes reach the halfway point of the shield. This consideration is crucial for achieving an even and aesthetically pleasing curl. If the lashes do not reach at least this point, it can lead to uneven lifting or curling, which may not provide the desired results and can affect the overall look of the eyelash perming service.

Choosing the appropriate size helps ensure that the perming solution is effectively applied and has the desired impact on the lashes. A properly sized shield accommodates the natural length and curve of the lashes, allowing for optimal lifting and curling while minimizing the risk of damage to the lashes.

Other factors, such as the fit of the shield and its price, may be relevant but secondary to ensuring that the lashes reach the ideal position on the shield for effective treatment.