Boxing promoters are always clamouring to find new talent rising up through the amateur ranks with dreams of turning professional. To find a boxing promoter who could get you (or a fighter you know) onto the professional stage, the best place to start is a local fight card.
Go to a fight card close to where you live. The promoter will be at ringside and isn't likely to have a crew of bodyguards if it's a small enough show. Yet, he or she will stand out clearly and will probably be introduced at least once to the crowd. Find some downtime in the action to introduce yourself to the promoter. In a few short sentences, explain your background and hopes to go pro. After a few pointed questions about your weight, ability, and age, you'll likely get a card and a request to call at a certain time.
If you can't get to a local card, get online and scour the web for promoters in your area. Most established promoters will have websites with contact information. Call or e-mail and explain your situation, you stats, and your plans for turning pro. Make sure you check out lesser-known promoters before you contact them. If you can, look at who they represent and contact those boxers directly. Once a particular promoter checks out, a phone call or e-mail could either open the door or get you nowhere, depending on the needs of that promoter.
To really stand out and attract promoters to your doorstep, document your ability with some video footage. Get digital footage of your fighting and sparring, your intense workout routines, and maybe even some character references from trainers and friends. Host the footage on YouTube, start a blog, and create multiple social profiles.
Promoters want two things beyond great ability in their fighters: people who can sell tickets, and people who can sell themselves. If you can use your spare time to create a real buzz around your pro debut and have tons of people in line for tickets before your fight is even set, promoters will go out of their way to find you and sign you. Use the Internet and all the available free promotional channels to pump up your reputation in the marketplace, and include your contact info and desire to go pro in all your content.
Go to the largest and most well-known boxing gym in your area. Talk to whoever runs the gym and see if you can work out there. Usually gym owners/operators, trainers and promoters have close relationships. Prove yourself in that gym--work out with any professionals in or around your weight class who train there, and show up every single day the gym is open. If your sheer skill doesn't get you noticed and connected with a promoter for your pro debut, your persistence will.