12 Important Rules, Most people learn these the expensive way.

Price falls 5% → Hold
Price falls 15% → Buy 10%
Price falls 25% → Buy 20%
Price falls 40% → Buy 30%
Price falls 60% → Buy 40%
Price rises 5% → Hold
Price rises 20% → Hold
Price rises 25% → Sell 10%
Price rises 40% → Sell 20%
Price rises 50% → Sell 35%
Price rises 70% → Sell 40%
Price rises 100% → Sell 90%

Always keep 10% as a moonbag
Never go all in, never go all out