Here is a wonderful video on learning a quick and simple way to keep your driver in play. It actually applies to every club in your bag, but I find it easier to learn by starting with the driver.
The most important key to this is taking practice swings. You need to swing without the ball until you are comfortable taking a full swing at various speeds.
Take the practice swing and then hold the finish long enough to remember what it felt like. Remember the feeling of being balanced and controlling speed. Then just repeat that feeling.
Just remember that it is not a three-quarter swing - it is a full swing at three-quarter speed.
You will find out that when you start to relax and slow the club down you will start to make very solid contact.
The importance of this was taught to me by the legendary Mickey Wright. How far I can hit a club and how far I should hit it are two different things.
The video only takes a couple of minutes and will be well worth your time. It and several more are posted on my YouTube Channel.