Trading journal
A record of every trade's setup, entry/exit, risk, result and emotional state. The only objective source for your mistakes and your real expectancy.
The journal should include a screenshot, the result in R, plan adherence (yes/no) and a short note. A weekly review lets you spot when you repeat the same mistake.
Numerical analysis (win rate, average R, performance by session/setup) shows which trades to drop; most traders' profits come from a few setups.