Being a great supplier with superior products and services is not always enough to get a foot in the door at some prospective customers, let alone enough to get orders. At some prospects, (e.g., some automotive "transplants"), interpersonal relationships carry great weight when suppliers are selected. Cultivating those interpersonal relationships can take years. This is where referrals can help open doors. But getting those referrals and capitalizing on them requires a well thought out and well executed plan.
The most obvious place to look for referrals is within your existing customer base. If you have been doing a great job for them, they may not refer you to their competitors, but they should be more than happy to refer you to key contacts at their customers, or acquaintances at other non-competing companies.