Read about the company you're looking to get a job with, see if there's any recent news articles online, look at their website.
Read the job description - they'll usually give a list of skills they want the candidate to have, try & think of at least one example for each one where you've displayed said skill.
Sometimes they'll ask what are your strengths & weaknesses so it's good to have an answer prepared - make sure the strengths you say match the skills required for the job.