Founder of Taillants d'Allure. Multiple Entrepreneur. Product Designer. Startup Doer and Advisor. Also: design geek, entrepreneur, marketer, startup fanboy, internet & social, PlayStation addict.
Normally you can contact the CEO. You must remember that most of the companies are not multinationals! Keep in mind that most of the worlds companies are small/ medium businesses. So, aim for the CEO.
If you are aiming to a big company... the target must be Human Resources, Quality Management Responsibles or Intermediate Managers.
Hope this was helpfull.
One of the most common is to set a monthly fee (recurring payment), or a retainer agreement. The purpose of a retainer fee is to ensure payment for future services or work to be rendered. Absent an agreement to the contrary, a retainer fee is refundable if the work is not performed.
Hope this will help.