The bigger the risk, the bigger the gain. If anybody is afraid of losing then put the money in a bank or in a vault no risk no gain. Take the risk if you succeed you will be happy if you lose you will become wise. it's a win win situation. But offcourse it defends on how you absorb the situation.
it depends, if you are using a leveraged account and you are trying to create a sell leveraged order on an exchange, it is obvious that you will lose a lot of money if something bad happens.
I prefer to stuck to low orders, like 0.01 BTC, or 0.10 BTC if you have a balance of over 10 BTC.