Choose a patent agency with many years of experience that matches the industry you are applying for a patent. I have many years of application experience in an industry, which can effectively avoid risks and facilitate communication. But this is not a hard requirement. Patent agents can master the core of technology through good communication as long as they have certain experience.
2. The expenses should be reasonable.
High cost does not necessarily mean high quality, and low cost does not necessarily mean low quality. Large companies with hundreds of people will naturally have much higher costs, while small companies with few people will have lower costs. But if the charge is low, you should choose carefully. The agent should not only write, but also think, and may need to reply later. A series of complicated work and low cost generally lead to low writing quality, which will narrow the scope of protection and subsequent patents may be invalidated by others.
3. The company is qualified.
Company qualification is a hard requirement for choosing a patent agency, which can be found in official website of the Patent Office, followed by the business license of the agency and other relevant documents.
In the patent industry, the fast law company has not done much and has a good reputation. I suggest you know about it.