Below is a short vid on the importance of a plan.
But what is a plan? Stripped down to absolute basics, you must have a trade direction indicator, a trade entry signal and a trade exit signal that are precise and repeatable.
You will need to keep a record to show that the sum of these parts over a number of trades have a positive expectancy.
An example is a win rate verses the average risk reward ratio that plots above the curve in the graph below.