What size undershirt should I wear to ensure not only a perfect fit but also ultimate comfort throughout the day? Is there a specific measurement, such as chest circumference or garment length, that I must take into account when making this critical decision? Furthermore, should I consider the fabric type and its shrinkage potential, as these factors might significantly influence the overall fit? In my quest for the ideal undershirt, is it prudent to consult a size chart, or should I perhaps rely on brands that I have tried and trusted in the past? Moreover, could my body type play a substantial role in determining the size I should select? If I am between sizes, how should I make that judgment call? Lastly, do different styles or cuts of undershirts require distinct sizing considerations, and how do I align these factors with my personal aesthetic preferences and lifestyle needs?