Prior to importing your data, it is important to scrub and cleanse the data. This means that it is important to understand the format in which NetSuite accepts data and that your data is logically segregated. Understand the sequence of data import eg: Import customer data and then their contacts. Addresses should also be broken out into various columns to meet NetSuite requirements or the way you intend for the field structure to be in NetSuite. Transaction level data is not recommended to be brought into NetSuite because of the heavy and potentially messy reconciliation process. The recommended practice is to bring open balances and open transactions so that operations do not suffer when moving into a new system.