For many job interview opportunities, you will first meet with a representative from Human Resources. The HR representative won't be working with you or even asking you many job specific questions. Instead, this individual is there to determine whether you'd fit in with the company culture, and if the hiring manager should take the time to meet with you. Getting past this interview can be a crucial step in landing the job.
The HR rep will ask you questions about your past work experience. This will probably include questions about your career trajectory and how it aligns with your goals. Make sure you lay out a clear career path that leads to you wanting this job. Show how all the prior moves you made (including education and learning new skills) have led you to your current goal of getting this job. You might also be asked why you are leaving your current job. Make sure to be diplomatic when discussing your past job, since it doesn't reflect well on you to bad-mouth your employer. Instead, use this opportunity to explain what you are looking for in a new opportunity, and how you want to take the next step in your career.
The HR rep might also ask why you want to work for the company. They are testing you with this question to see if you have conducted any research, and if you are enthusiastic about this company or are just looking for any type of job. Make sure you do your research before going in. Come prepared knowing what the company does, who their competitors are, and what it is about the company that aligns with your career goals.
'tell me about a time'
Lastly, the HR rep might ask you to describe a tough social situation at work or to tell them about a time you had to succeed in difficult circumstances. The key to these questions is providing concrete evidence of success. It is important to give a detailed example - bonus points if your example pertains to this current job. Even if it doesn't, your example still needs to be specific. You should provide a background to the situation, explain the actions you took, and then detail the (positive) outcome of your actions.
Most of all, remember that an HR rep is looking to see if you are confident, poised and enthusiastic about the job. Keeping these qualities in mind will help you ace that job interview.