Which service would require a client to have a consultation before proceeding?

A consultation is crucial before proceeding with chemical hair treatments because these services involve significant alterations to the hair's structure and composition. Chemical treatments can include processes such as perming, relaxing, or hair straightening, which may have varying effects based on the client’s hair type, history, and overall health. During the consultation, the stylist assesses the client's hair condition, discusses previous chemical services they might have had, and identifies any potential allergies or sensitivities. This step ensures that the treatment chosen is suitable for the client's specific needs and minimizes the risk of adverse reactions or damage to the hair.

In contrast, hair coloring, while also often benefiting from a consultation, tends to follow more straightforward guidelines and can often be applied without as extensive a discussion regarding hair structure—as long as areas like allergies are checked. Basic haircuts and shampooing and conditioning are routine services that normally do not require a detailed consultation, as they involve less modification of the hair's structure and are typically safe for any client, assuming they have no specific concerns or requests.