Having a rough interview? Even if you give stellar responses in an interview, an interviewer expects other things but never tells you.
Research
Show them you've done your research.
The company has already looked into you, so you need to spend time researching if this particular company is right for you.
Before you even apply for the job, vet the company. Dig through their website, read their blog, follow them on social media and see what interests you.
This will give you a feel for the company culture and how well you'll enjoy working there. It also lets you know what to highlight in your answers. If the company works closely with a charity you volunteer for, bring it up. Once the interviewer knows you've taken the time to look into the company, they'll see how serious you are about the job.