I would advise you avoid lending as a way of earning BTC income. It's not a safe practice to engage in actively. If you do decide to lend, be very picky about who you trade with. It might not seem like it will make you more BTC more quickly, but it will certainly protect you from fraud.
That being said and to answer your question:
So far I have:
As a new user, for my piece of mind, I can only lend to trusted users who have borrowed and paid back before
As a new user,for the users piece of mind, an escrow service will be needed
as a new user, a max of 0.1btc at 5% interest is sufficient until more trust is gained
Also, I know the first piece of advice a lot of you will give me is "Dont do it!", and depening on the outcome of this thread, I might not. But i'd like to know
Good general rules to start with. I would also add "Only lend to users who provide collateral worth 110% or more." There's a topic here in the Lending subforum that talks about requiring collateral, but in a nutshell: it will give you assurance that you can recoup your losses should a lendee be either unable or unwilling to pay you back. The collateral topic has some good ideas for acceptable collateral.
I would also avoid loans to people who aren't willing to share why they need the loan and how they intend to pay it back (i.e. what kind of income do they have?)