I have heard and also read in various threads that mining is too risky. The invested money can all be gone with a blink of eye. Actually i am not sure wither i should do it or not. If i invest, then is there any chance to loss all the money?
If i invest, then what should be the amount first?
And in which sites would be better to do mining?
With the response you received above Im pretty sure you have gained some idea now.
But you know there is "real cloudmining" but considering the current bitcoin mining difficulty and rewards, even we have lots of legit cloudmining operation around, it's really not profitable to invest on those today. And how much you will invest;
BTC0.01,
BTC0.05,
BTC0.1? That's not enough.
Better find other method to earn bitcoin and forget passive income for now. Work for it actively than rely on other services that will automatically gained you profits.