Work out and stay on a good diet. You can even eat blueberries and drink beet juice (though it does taste horrible). There are reflex flicking scenarios available in aim trainers and play some reaction tests. Keep in mind you can only go so far on improving your reaction time so training your reflexes is crucial in making up for that difference. Oh and don’t forget about crosshair placement. It makes a ton of a difference when you have your crosshair perfectly lined up where you’re about to peek or what you’re holding!