Each one would work different. There is not one way they all work. There are some I would avoid.
First lending as it is really hard to get the money back if they default, I suggest staying clear of it. Second one that just jumped out to me was
Casino Investment. I would also avoid casinos in general as a investment. Just not enough regulation.
I'm sure there are more that are ones I don't agree with, but everyone has different factors they want. I would make sure before any of them to do your own research. I strongly push for new people to do research before investing.
Good opinions, but every investment can be safe if you risk little amounts.
I would certainly not put all my savings in a mining contract or similar.
It does lesson the risk of losing a lot but I see problems. A lot of scams start out paying out... so that first payment the small one you might ROI on. Then some will expand and it craps out from being a scam. A lot sadly have done this where first in got money and last in got taken for a ride.
And loans I just don't like as getting money from a default seems pretty hard. Even BTCJam you would think would have a unit or something to help with it... but they just release the persons info to you and expect you to take whatever legal route there is. If a website actually took a role in helping get defaulted money back they could easily take over as best site to loans at.