I know I am quick to anger. How do I improve before I marry?

This awareness is already a valuable first step; use it to build new habits before there is a spouse who bears the effects. Note every time you get angry for two weeks: what triggered it, what you felt in your body, and what you said. The pattern will show you where you need to act. Practise a stopping technique, such as falling silent and changing your position. The Prophet ﷺ said: “When one of you becomes angry while standing, let him sit down. If the anger leaves him, well and good; otherwise let him lie down” (Sunan Abu Dawud 4782). Apologise immediately every time you go too far, even to your siblings. If your anger has ever led to breaking things or frightening people, get a counsellor's help now. See managing a hot temper.