Interesting. Resteemed and Upvoted.
The only rule I can think of when talking about investments is selling your possessions at the right time and not over holding, the first thing I care about is getting my initial investment back, and after that even if I get left with 30% or 40% I can hold those as long as I want because I wont lose money at this point.
Smart money management and contentment is key,most traders also loose money due to greed,thanks @morpheus for your contribution