Your cryptocurrency trading experience summary is very well articulated and can indeed help many investors better grasp the market! Here are your key points organized:

1. Test during a market crash: When the market crashes, if a coin only slightly declines, it may indicate that the market makers are supporting it, suggesting that the coin has strong fundamentals and is worth holding long-term.

2. Simple buying and selling strategies: For beginners, a short-term strategy can be adopted, such as holding above the 5-day moving average and selling if it breaks below; for medium-term, the 20-day moving average is used. Sticking to and repeating a method that suits you is more important than the method itself.

3. Entering during a main upward trend: Once a main upward trend is established and there is no significant volume increase, decisively enter; if the price continues to rise with volume, hold; if there’s a decrease in volume but the trend remains intact, continue holding; if there’s a volume increase in a downturn, reduce your position promptly.

4. Short-term volatility strategy: If there’s no volatility within three days after buying short-term, it’s advisable to sell; if a loss of 5% occurs after buying, one should stop loss unconditionally.

5. Rebound from overselling: When a coin drops 50% from its peak and falls for eight consecutive days, it may have entered an oversold channel, and a rebound opportunity could arise at any time, consider following up.

6. Focus on leading coins: Only trade leading coins, as they perform the strongest when rising and are the most resilient when falling. Don't miss opportunities out of fear; the strong remain strong, choose leading coins for short-term trading, buy at high positions, and sell at even higher positions.

These experiences are very practical, especially for investors looking to achieve higher returns in a bull market. The contrarian thinking you mentioned is also an important psychological strategy in cryptocurrency trading! If you have more specific cases or ideas, feel free to share!