I have a bit of coin to lend, but I want to do it as safely as possible. The lower the risk the more I can loan.
Can anyone give some advice on how they have been able to do this with loans of 5BTC and up?
Collateral of course makes the most sense, but it is a difficult arrangement, especially for tangible assets.
The best way to stay safe has always been with collateral. If possible you should loan to those you've met before in real life and can judge their character (doesn't matter so much with collateral). That being said, nowadays there aren't that many significant loans (in size) that can afford to be collateralized by the borrower so you're assuming a lot of risk by lending that much without collateral.
Considering that you're willing to lend upwards of 3K, physical assets are a viable option as collateral provided you're in the same country as the borrower (as fees for shipping will be insignificant in comparison to the interest from the loan) so you'd be best to explore that option. People usually don't have enough digital collateral (usually altcoins) to reach 3K and you might not want it as they can be rather volatile.