I've been lending with Zidisha for almost a year now.
My way is to use the automated lending feature. If you want to preserve your funds long term you need to set your interest rate to at least 10% in order to offset losses from people defaulting (although I think Zidisha are getting better at screening the borrowers as time goes by). I set the automated lending feature to lend to whoever's loan application is going to expire soonest. It lends out $10 for each borrower. I have $1000 in Zidisha, so I have a large portfolio of borrowers.