What are the most crucial things to look for when researching companies you want to work for? Where?

This fall ill be going to my business career fair and since its my Junior year the internship i get hopefully turns into a full-time offer the following year. I made a list of 15-16 different companies that i recognize and meet my size criteria. Im trying to narrow it down to a handful.

What are some good first steps to take such as things i should be looking for and what are some good resources to look at when trying to narrow down companies?

usa jobs
usa jobs resume
usa hotel jobs
usajobs
usa jobs federal government
usa job in ksa
usa jobs
usa jobs login
usa jobs gov
usajobs.gov
www.usajobs.gov
usajobs.com
usajobs
usajobs.gov official