Although the specific process may vary somewhat, the process generally starts with by designing the brand itself. Next, fill out a brand application and mail it with your design and any necessary fees to your state's department of agriculture.
Some states may have different agencies overseeing brand registration. For example, in Texas, you can register a brand with your county clerk's office. Check the website for your state's department of agriculture for specific information on which agency to register your brand with, or ask your local cattle raisers association for help.
Some states, such as Washington, require you to send in three separate brand designs. This is because they require a unique design, so submitting multiple options makes it more likely that you can get a brand of your own design. If all three are taken, the agency may send suggested options back for you to select.
Other states, such as Texas, allow duplicate brands. They require you to choose a different location on the animal's body. For example, if the existing brand is placed on the left shoulder, you may be able to register a duplicate brand on the animal's right hip.
Be sure to read your state's design requirements thoroughly before creating your brand. Some states require a certain number of symbols in the design or have other requirements or restrictions.