Looking to get an entry level job in marketing/advertising(or business related) for the summer possibly longer once I start business school in Sept. Problem is I have no experience and I need to bullshit my resume. Anyone in that field or related to business in which you can give me a few tips on what to write as previous job duties?

Also, I am going agency to agency since CL/Indeed etc are all a waste of time and I will never hear from anyone because of the volume of email they receive. Any good intro I can start off with or mention so that they will consider me? TIA