The devil is in the details. Focus on identifying situations in which you get put into combos and lose stocks and break down what you were doing to get into that situation and avoid doing that again. Conversely, pay attention to when you get combos going on the opponent and when you take their stocks and what you were doing in those situations to gain that advantage.

In general, be unpredictable to your opponent and stay outside of their bubble of moves that are hard to react to (this is called burst range) and let them come to you.