How do you vet a corporation?

Be it you want to do business with them, want to invest in them, or are considering whether or not to get hired by them, how can you get the most accurate info on a company beforehand?

I am relatively green when it comes to evaluating a company’s health, wealth and size based on data floating around, so sorry if I’m asking the wrong questions here (in which case direct me to the right ones please).

The particular company I am trying to get some info on seems relatively fresh, i.e. 2003/2007 fresh (depending on the branch). I know it’s listed on the TWSE, it’s got branches all over the world, though it’s relatively non-existent on the web. And of course their website is not of much help either (and a weakly made website always raises a red flag for me in such cases). Any suggestions? it’s in the biochem industry btw – is there an index I could check or something?

So yeah, how does one go about veting a corporation?