building a business as a youngster with no Formal experience

Hello everyone. I find myself in an interesting position.Long story short is this. I was approached by the owner of my local coffee shop at which I am a regular customer. Found myself discussing my current schooling and the fact that I am pursuing my second undergraduate year of marketing was interesting to him. He sat me down and expressed an interest in creating a sort of inner circle, looking to expand the business and is interested in having me oversee marketing efforts, as well as the possibility of me becoming a partner.This coffee shop currently has one location, with a second about to be constructed as well as a potential third possibly in the works.I have an above average knowledge of social media, having used it to ship my photography page, as well as some experience creating content.I also have some formal education from 2 years of an undergraduate degree, and some ambitious ideas that this guy seemed to love right off the bat.But as someone who is only 19 and never held such a responsibility, how do I go about making sure I dont bite off more than I can chew? I trust my capability to bring value to their brand, I am a supporter of the product and can attest to the customer experience these guys foster being remarkable. Having never navigated these waters, I do not want to get overzealous.Thank you for your time, first time poster. Much love. via /r/business http://ift.tt/2F4xGGb