To maximize your Pyrex measuring cup's effectiveness in the microwave, it's essential to follow a few guidelines. First, always ensure that the cup is labeled as microwave-safe. While most Pyrex measuring cups are, it’s a good practice to double-check the manufacturer's recommendations. Additionally, when microwaving liquids, fill the cup only to the specified maximum fill line. This prevents overflow caused by boiling or steam buildup, which can lead to a messy microwave.