How can I approach a brand for sponsorship if I don't have any existing connections?

Coming in through the front door without any referral almost never works. You need to build relationships first - if you can't get anyone to endorse you, sponsors question why they should want you representing them. Start by connecting with athletes who are already sponsored by your target brand and ask them for advice. Develop relationships with people who might recommend you. If you're approaching a brand, don't pitch right away - instead ask specific questions or seek advice. Referrals from people the brand already knows and trusts are essential for getting past the first round of consideration.