Don't be afraid of fail but don't use trading like gambling. Be careful, act after your own research. These principle are important, indeed. Be ready to loose some amount of money and never trade without clear understanding how much money you are ready to loose.
You have stated it just as it is reinforcing my ideas, but mind you failure in trading is not a principle.
Do not forget to learn proper trading principles, ta or fa, or chart anaylsis. and only invest amount that you are able to lose