How do they bill you? Most legitimate mentors (for hire) will charge by the hour. Most illegitimate mentor services charge a large up front fee for X number of sessions in X number of weeks (or months). The difference is if you find the advice worth less than you expected, you don't call the per hour person back and you only lose the price of a session or two. If you find the advice of the large up front fee people worthless you have to fight like hell to get your money back against people who likely make their money by not giving refunds.