Entries get the attention. Exits decide the results. There are only three basic exits, and each has a place.
A pre-defined level where you take the whole position off. Best when the move is event-driven — an earnings reaction, a scheduled print — and mean-reverting afterwards. Weakness: capping the occasional large winner that funds the year.
You give back some of the move to stay in the ones that keep running. Best in trends. Weakness: repeated small give-backs feel worse than they cost, so people abandon it right before a big trend arrives.
If the reason for the trade has not shown up in N bars, you leave. The most underused exit. Best when your thesis was "this should move now".
Write the exit into the trade at entry — the journal has fields for it, and the review page will eventually show whether your exits or your entries are the problem.