Ernie,
Welcome. You will find that most of the regular participants on this forum were lenders during 2006-08, a period referred to as "Prosper 1.0," when the rules for lending were different from today. Furthermore, most of the former lenders here were disappointed with their experience using Prosper 1.0, or at the very least decided they had enough of their experiment with Prosper by the time the company entered an SEC-required "Quiet Period" in late 2008. Some moved on to Lendingclub.com, and some gave up peer-to-peer lending altogether. A small handful continued lending under today's rules when Prosper reopened in 2009, though recently I've even seen some of them give up on Prosper, claiming it's now stacked in favor of institutional investors.
So, I'm not sure you'll find a lot of the "seasoned" advice you're looking for. However, this is a smart and entertaining bunch of folks regardless, so you may enjoy looking around anyway.