What are some tactics I can use for finding the gems amongst the huge pile of regens? What kind of stats would they have at a young age and how do I know if they have the potential to become great?
All of these factors will weigh up and given the right amount of time you will be able to find top class players (not necessarily like Messi) but still.
NB: There is also a program you can download that runs in parallel for FM2013. It is called FM Genie Scout which basically queries the database and returns a load of readable data for you. You can select a position and then order by the players with the most potential in this position and buy them (even tells you how much is likely to succeed in an offer). They are aiming for a 9th December release for this