You are responsible for ensuring that the mark you choose does not violate someone's trademark. It is your responsibility to conduct a trademark search to ensure that the mark being considered is not in use. There is no easy way to do this, and even the most extensive search may not be 100 percent guaranteed. Ignorance of trademark rights and rules is not a defense against infringement claims or lawsuits.
An inexpensive way to conduct a search is through the Internet or by searching the United States Patent and Trademark Office's Trademark Electronic Search System. Another way to conduct the search is by hiring a trademark attorney. The attorney can either do an in-house search or use the services of a trademark searching company. He can then review the results of the search and provide the client with an opinion regarding use of the mark. This approach, however, could be costly.
After you have decided on the mark to use, you can take advantage of your common law rights by using your mark in commerce, so long as your use does not violate another party's trademark rights. However, these rights are limited to the geographic area where you use the mark or can demonstrate planned use for the mark. You may expand upon your common law trademark rights by registering the mark in your state or federally through the U.S. Patent and Trademark Office. Registration of the mark provides ownership notice to the public and provides additional benefits and protections should you need to file an infringement lawsuit in the future.
It is your responsibility as trademark owner to police the use of your mark. You can conduct regular Internet searches to check if your mark is being used by someone else; however, such searches may not find every potential violation. You can also use the services of a trademark search company and pay for "watch" services to receive regular reports of pending trademark applications, domain name watches and common law uses of marks that may be similar to yours.