On p. 89 of my book, I give an example of a follow-up phone call with a headhunter. In the example, I started the conversation by calling myself "Dr. Brett Jiu." Some readers wonder if this sounds a little too pretentious. The answer is: it depends. In fact, it seems the norm for people with doctorates in Europe to call themselves "Dr. So-and-So" all the time. In the U.S., the practice is less prevalent, mainly because the Dr. prefix usually implies a physician, a medical doctor.
When you address someone higher on the job market hierarchy, i.e., a potential employer or a useful contact, it’s important to address the person by "Dr." if he or she has a doctorate, as discussed in the book, unless you know the person very well and have always been on a first-name basis with him or her.
When it comes to yourself, the usage depends on the situation. If the person you are talking to is a headhunter or recruiter, it’s completely up to you whether you prefix your name with "Dr." I would not shy away from calling myself "Dr. Brett Jiu," although, truth be told, I rarely do that. Some people have a natural presence in any kind of business or social situation, and when they call themselves "Dr."-something, people respect them even more. But if you are a down-to-earth, easy-going kind of Ph.D., you may just elect to omit using the Dr. prefix. Again, it’s up to you.
Of course, if the person you’re talking to is a potential employer, I don’t think you’d want to call yourself "Dr," regardless of whether he or she also has a doctorate. When addressing someone superior in rank, it’s always to just refer to yourself by your first name (given name).