Keep a trading journal where you record all your trades, the reasons for entry/exit, and the profit or loss incurred.
You may also want to include any other relevant factors that you may want to examine to determine their impact on your performance. This could include anything from the time of day to your general mood, sleep, exercise, or eating habits.
Schedule time to go over your trading journal once a week or month.
Look through the trades that went poorly. Identify strategies or trading setups that need tweaking or that you might want to avoid entirely. Were there any assets or timeframes where you just can't seem to win? Keep an eye out for any other factors that might have caused you to trade poorly. If you realize that you end up losing money 80% of the time if trading while angry, you can give yourself a rule to never trade while angry.
Do the same for the trades that went well. Did you do particularly well on certain assets or timeframes? Evaluate which strategies or setups performed well for you and consider focusing more on them in the future. You may also find that you tend to have more profitable days when you sleep more hours or exercise in the morning.
If you do this regularly and consistently, you will gradually be able to identify the best trading strategies and habits that are best suited to making you a profitable trader.