How to decide sell/buy point?

Follow the current trend to buy/sell

Investment is very simple, you can just follow the trend; but sometimes it’s extremely hard for human nature.Investors like to complicate the simple things, and they are anxious about the buying/selling points. I think the way to profit is not to see the market correctly, but to have the arrogance to gain a lot when you follow the trend properly, and the courage to face the failure. Investors must learn to move forward in the mist and strengthen their confidence.
1. Cut loss and let profit run
I think investment is essentially a risk management game, not a profit-seeking. We have to set the stop loss level reasonably, since the indicator is what we can control, the profit is controlled by the market.
Recently I pay attention to   $Lucid Group (LCID.US)$  which is the combination of   $Tesla (TSLA.US)$ and   $Ferrari (RACE.US)$ , I like this new energy car which appearance is high-end, so I bought the stock at $22.
2. Buying stocks is buying companies
Trend investors buy at a high price after an uptrend is formed which take advantage of the trend, and sell them at a higher price when the market changes. When buying at a low price and the downtrend is forming, they should sell them at a lower price decisively so as not to loss much. Stock picking is not as good as picking time, and picking time is inferior to picking momentum.
For example, once my dad posited in   $Sea (SE.US)$  at 35 dollars, now the price has risen 10 times. This company directly copied the business models of   $TENCENT (00700.HK)$  and   $Alibaba (BABA.US)$  to Southeast Asia, and has ranked first in games and e-commerce in most countries. I am very optimistic about the company, so I bought it.
3. Read more investment books
I like to find answers in books, so I read a lot of classics which are written by Warren E. Buffett/Philip A. Fisher/Charlie Thomas Munger/Benjamin Graham/John Templeton/Peter Lynch. The stock market rises slowly but falls quickly, because the explosive power of fear far exceeds the desire of greed. The prices need purchasing power to rise, but can fall freely as long as their own gravity! Buffett said: "As long as an investor can avoid big mistakes, he won't worry about it next ".
There is no “best” points for buying/selling, what we can do is to find the "most suitable" one. Every point of the transaction is the result of careful consideration, but there is no guarantee that every step is correct. I have heard lots of theories which are so difficult to implement. It is difficult to invest in terms of waiting, upholding and being emotional. Fundamentally speaking, it’s hard for us to break through ourselves.