Final answer:
Successful designers and stylists should monitor seasonal trends as they directly impact fashion collections. They can also gain inspiration from underground trends, which may eventually influence mainstream fashion.
Step-by-step explanation:
Successful designers and stylists should keep a close eye on seasonal trends. These trends are heavily influenced by a variety of factors, including cultural events, fashion weeks, and changes in consumer behavior with the seasons. For example, lightweight fabrics and brighter colors often become popular during spring and summer, while heavier materials and darker tones are typically in vogue during autumn and winter.
In addition to seasonal trends, staying updated with underground trends can also be beneficial for designers and stylists. These trends often originate from subcultures and can eventually influence mainstream fashion. However, the most immediate impact on their work is usually from seasonal changes, as the fashion industry operates on a seasonal cycle with collections released several months in advance.