1) Visit the company's website to know more about the company and be sure its not a scam job update.
2) Check the company's social media pages... twitter, instagram, facebook, etc and linkedin page to know how the company wants its consumers to see it.
3) Get an interview edge.. you can find out people who have interviewed with the company before and get to know how the interview experience was like.
4) Check company review pages. Here you see what present and past employees are saying about the company, you know about their company culture and many others.
5) Check salary websites to know how much the company is paying, compare with other companies and field, and find out how much you are worth to enable you answer the salary question and negotiate well during the interview.

Goodluck and Happy New Week.