Final answer:
Before making a pivot table, remove blank rows and columns, ensure unique headers for each column, and unmerge any merged cells.
Step-by-step explanation:
Before creating a pivot table, it is important to prepare your dataset to ensure the pivot table functions correctly and efficiently. One essential step in this preparation is to remove any blank rows or columns within your data. These can cause errors in the pivot table or result in incorrect calculations. Additionally, ensure that each column in your data set has a unique header, and that there are no merged cells, as these can also interfere with the pivot table's ability to accurately categorize and summarize the data.