The fastest way is to get a good coach, develop a solid foundation of proper strokes and grips, and hit a lot of balls. Most real people find this difficult due some combination of time and money, but that's the fastest way.
Beyond that I don't think there are any gimmicks. A 4.5 is a very solid player. They can hit hard, with spin, direction and pace, can hit every shot at least passably and most shots pretty well. You can teach yourself, you can not play every day, but then it will take longer.