Aspects of the subject disclosure may include, for example, receiving from a campaign manager device information defining a line item in an online advertising system, including receiving information defining constraints for the line item. The subject disclosure may further include collecting browsing history information for targetable users matching the constraints for the line item, generating a machine learning model to rank the targetable users and building a new segment based on users ranked by the model. The subject disclosure may further include providing, to the campaign manager device, a recommendation to add the new segment to the line item, receiving from the campaign manager device an indication to attach the new segment to the line item, and subsequently, providing advertisement content to targeted users according to the line item including the new segment. Other embodiments are disclosed.