I've been working since 6 years ago and one of the things that I've suffered is being rejected from good job offers because my technical level. Now this is frustrating because you know that you can handle with the resposibilities of the job, but when you are on the technical interview is difficult to demonstrate. So here are some tricks that I've learned.
Everybody is always scared. And when you need to answer something that you don't know, or you feel no confidence of your skills, this is demonstrated in the way we talk. But don't be afraid to tell "I don't know" or talk about something you know. If you commit a mistake is not a proof of you lack of knowledge. Nobody can master 100% a technology.
After a time, I started to do this trick. Why? Because sometimes this knowledge was frecuently asked by other interviewers. So I started to annotate any concept that I didn't know to research it later.
When you're working, taking interviews is very difficult. Commonly I requested the interviews after my work time, but many times the interviewers can only during the work hours. So in those cases is necessary plan your schedule for the interview. Maybe during the lunch time or in the afternoon when you don't have too much meetings. Also find a place in your work where you can take the call with no problems.
Many times I've received job offers that sound great, but when I was on the interview, I didn't know many of the questions and that was because I didn't know the technology. So always ask about the job requirements.
Your resume must be always the honest vision of your professional background. If you add that you know a technology, you must know that technology, or don't add that to you resume. What you add to your resume, are the weapons that you give to the interviewer for test your knowledge.
In this times, you must be updated about the technologies that we must use. And with many technologies, we need to be sure that what we're learning is valuable in a company. The job offers gives you an idea of what you should be learning.
Finally, sorry for my english. I'm non-english-native speaker so if you have any comment, please help me to improve my language skills.