The Sith most commonly draw from orphans and the extremely wealthy, although this is a bit looser within the Sith Empire.  Sith apprentices are usually the most elite people that can be found, as opposed to the jedi who take in everybody.<br/><br/>Nar Shadaa is basically a hive of Sith potential, as would be much of Taris.  Corellia and Alderaan, as human homeworlds, can also provide powerful Sith.  Revan might have left a few children on Tatooine, though really anything more happening in the galaxy on tatooine would be utterly rediculous.  (B'Moarrs might indulge in spiritual practices which lead to alchemy though)<br/><br/>And of course, there's the tried and true route of being a Dark Jedi.