So, my friends and I have been interested in possibly picking up a 3 to 4 player co-op game such as Borderlands 2. However, I have no idea where to get us started or what we need to be successful. I've looked through the resources but can only find a 2 player tutorial. Does much change with the addition of more players?

Do we need certain save files / a certain patch / certain team composition? any answers would be appreciated.