Synopsis
Wholesale sites may want all new customers to be in non-0 customer levels.
Procedure
Change the default value for the CustomerLevel field in the Customer table in the database to the default value you wish to use. That default is set to 0 out of the box, so that all customers are registered as "retail" customers.
NOTE: In ML version 7.1.0.0 and beyond, this can also be accomplished with the DefaultCustomerLevelID AppConfig.