Essential Concepts to Master Before First Purchase?

[Josh R. Dunwoody]

I am planning to make my first investment purchase early this year - preferably a multi-family buy and hold. Maybe a flip if the deal is right. I am working to educate myself with podcasts, webcasts, forums and several REI books. I want to avoid major mistakes but also feel I am starting to drown in information and want to take action. I know I will learn most by doing (like everyone else!) but want to set myself up for as much success as possible. What are the most critical analysis tools/concepts I need to master prior to making that first purchase?

Thanks for your advice and experience!

Josh