Do your own thorough research and never go all in. Different strategies exist that could work for some persons and won't work for others but the use of stop loss could go for everyone, for it may be a universal strategy
A trader should always have it at the back of his mind that losses is possible in trading, a trader should use the amount of money he can be able to afford to lose is the first point. Experience helps better than anything else, the more the experience afttler appropriate research and mistakes will help the trader to have a profiting strategy. Trading is more about experience and losses can not be avoided until more are experienced