how to establish confidence in buying and selling altcoin because when looking at the price down and immediately want to sell even loss
Having a loss will always be a part on your trading journey, the first loss is hard to overcome and might destroy your confidence doing another trade but everyone has its share of losing in trading.
You just have to think positively when doing trade and dont think about the price drop, eventually as you do more trade you gain experience and your confidence will built up a long the way.