1. Open both eyes wide before buying - Read, see, observe, study, think. Do your homework (FA, companies leadership, culture, vision, order book, cash flow, etc). Then have a strategy and price-action using TA to determine entry point. Investment timeframe is at least 3 to 5 years.
2. Close one eye after buying - After you purchased the stock, relax and do not waste too much time to monitor or track price fluctuations. If you like, do a yearly or half yearly review.
To me, it is quite similar to marriage. Before marriage, open both eyes wide to choose the appropriate spouse. Do FA - upfront decide on what character & qualities that will match yours & have best likelihood of long term growth together. Of course, you must plan to be the best possible spouse and do not walk away at slightest hint of problems. (Same as not selling stocks at first sign of volatility, if you have done your thorough homework).
I think too many marriages ended in divorce because young people close one eye during courtship and open both eyes wide after marriage. During courtship, did not do their homework (ie FA, etc). After marriage, see all the faults & problems, and go their separate way. Same as dumping stocks & making huge losses because very little or no prior homework was done.
Money can be made in stock markets. But it requires us to invest time, effort and use our brains. Do not be greedy or simply follow the crowd. Nobody plans to fail, but problem is majority fails to plan. So likelihood of failure is high.
Enjoy life & enjoy making your money grow & multiply. Do not simply put your money into bank accounts & allow inflation to erode your savings through pittance bank interest.
Wish everyone good health and happiness.

Bull gone on for far too long. With very high inflation, interest rates going up & tapering by Fed, no "free" govt handouts of easy money to buy stocks, etc etc all happening around same time... I believe a crash is coming soon. And charts showing a likely double top for both S&P 500 and DJI. Crypto frenzy will add to the crash too.