You can work with anyone who is willing to work with an independent contractor. We welcome people who want to work to become a successful independent contractors. For this we handle the tickets, and help you with your questions and other travel documentation. After a time your sales will let you deal directly with travel providers and at that time you're on your own. To be an independent contractor and work with us or any other agency you must form your own company.
Every state has different requirements for starting a business.
The FEDS also have requirements and they differ depending on whether you form an S Corp, partnership or sole proprietor. Calif. has more complicated rules. You'll need to check with your own state and local authority. To sell any travel products you need to try them and judge their value and quality. You will also have to go to trade shows that take you on tours of the cruise ships and cruise over and over again.