I think one of the most important things someone can do before they even apply to a company is to do their homework. What I mean by that is to really dig in deep and find out about the working environment, progression, pay, culture, values, everything. Find out about everything that is important to you.
You can find all of the information on a company’s website. Another great source of information is finding people who work at that company and follow them on Twitter or Linkedin and ask them directly how they like working there, find out about the culture, progression, etc. Another great way of conducting your research is to that company and interview them at a career fair. You need to make sure you would be happy working there if you were offered a position today.