Emotions, first thing that comes to my mind is having control over emotions. If anyone asks me about learning trading, first I will ask them if they have the will to rely on data analysis and strategy rather than taking decision based on their emotions. This is a very important thing in trading, which many people ignores, thinking that it's not that important. This is the reason why they face those problems which you have mentioned.

Also when learning trading, you should always start with low amount. Try out your strategy and skills, and then go for the big round.