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.