For me the most important thing was to feel that I was selling myself, rather like a salesman does with his products. Why should you buy this pair of shoes and not others? Why buy my food when someone else has the same? In interview terms this translates as: Why do you wish to work for us? Why should we employ you? In other words, what have you got to offer?
Study the Job description, as some questions will come from it, but many a time you may not know something and still get the job. They must feel your hunger; your loyalty; your Team spirit, your humility with strength.
Apologise if you don't know, while coming straight back with the fact that you really want the job, and will do your best to learn quickly. Of course they must feel this. Be sincere, and you can only do this, if you really want the job. So choose something that you like.
Finally, dress smartly, write well even on application forms and carry yourself well at interviews. Look up, smile, shake hands before sitting down, appear confident. Be weary about discussing salary before you feel confident to do so. Do not over sell your virtues or experience. Be balanced. Do not talk too little or two much.
Be kind, brave, appear caring and courteous ...be fluent in speech and conviction. A good CV is great, but remember all these other things. Prepare but sometimes very little on the subject may come, as they will look for the things mentioned. What are your strengths? What are your weaknesses. Ponder these well and present them well if asked.
Some interviewers will also use scenarios, maths or care plans or presentations, according to the nature of the job. Be prepared. Best wishes.