Been trading for almost 30 years now. Have done fundamentals, daytrading and now technical swing trading (and teaching coworkers, families, friends, neighbors).
Rules of stock trading I have used are:
- Market knows everything - Share price reflects everything - Technicals are more accurate than fundamentals - BUY low and SELL high if LONG - BUY high and SELL higher if stock is trending - BUY high and SELL low if SHORT
We are human and make mistakes. If your timing was off and lost 5-10%, you can always admit your mistake and sell at a small loss.
Why would you hold unto a stock that is falling in value? How long would you hold your hand on a hot stove? That's right, not long.