How to attract potential sponsors for a Competitive Fitness Athlete?

My girlfriend is a competitive fitness athlete. She compete as a figure athlete in bodybuilding shows. She also competes in Powerlifting, Tough Mudder and Spartan race competitions. Here and there she gets offered sponsorships, but has politely turned them down. The main reason being we don’t know what would be a good sponsorship and what is reasonable as far as her requirements. We'd like to pursue this avenue for a few reasons. Revenue being the main one, but also building a brand for her, so she can have an effective platform to motivate inspire other women in their 40’s and 50’s. I’m looking for someone who can outline the major and minors dos and donts we should be aware. How do we go about creating “her platform.” What she should offer? How do we go about attracting legitimate offers. She has no aspirations of being famous, but we both feel we can generate some good revenue and have a positive impact by partnering with companies. Can you offer any detailed advice or outline? Thanks