My biggest problem in trading is that I was too brave to buy altcoin at a high price, and because of that I often lost my btc, even once I lost 50% of my btc when I bought altcoin at a price far above ICO.
So please give me feedback on this, what should I do?
You've got your answer already. The problem is that you buy altcoins when they are too high in value. That is opposite to the basic rule in trading which is buy low and then sell high. That is what you should do next time. Try to buy during dips if you can. Avoid confronting the charts with your emotion.
before we buy, we need to analyze the coins and we must know how much price we want to buy to avoid or prevent from the down. but if after we buy the price is down again, then the only one we can do is we don't sell because of panic or we can buy more in lower price and waiting the price is back. I am suggesting to not invest in the ico, its better if you do trading because the chance for you to make big profit is wide open.