Practice, practice, practice

Practice doesn't make perfect, it just makes it permanent. You need to repeat drills, movement, actions that work no matter what. Then those same actions will surface when your are under pressure, when you need to deliver a blow to your opponent. Otherwise you will perform washed down, wimpy, non effective techniques. And THAT will get you killed. If you are at the point where you need to fight back, fight back with power and effectiveness. Otherwise you will just be provoking your opponent to fight back and since he is most likely stronger and bigger than you (we rarely get attack by smaller and weaker people) you just gave him the chance and motivation to win.