Choosing the right type of driver for your swing is very important. It is important to know the speed of your swing, if you are able to generate club head speeds over 100mph then you need to make sure to use a driver that has around 9 to 9.5 degrees of loft and a stiff to super stiff shaft. If your club head speed is less then you should consider a driver with around 10 to 10.5 degrees of loft and a regular or senior flex so you can get the most distance.
Getting lag is one of the secrets to hitting the ball a long way. Lag refers to the angle formed between the club and the left hand (for right handed players). The idea is to release this at the last possible moment to maximize club head speed. One tip to help you get more lag is to keep the dominant arm passive and also to use very light grip pressure. Another swing tip to help you generate more lag is to think about pulling the club with the left hand (right handed players) on the downswing as this will encourage a more inside to out swing path which is ideal for straight shots.
Remember also to swing within yourself as this is key to not just hitting the ball far but to also do it on a consistent basis. Also, learning to hit a slight draw is ideal for getting the most distance from your drives especially if you are facing a strong head wind. A draw will also give you more roll on the fairway resulting in longer drives. While physical strength is not the most important factor in long drives, it cannot hurt to lose weight if you need to through dieting and exercise. Also doing weight training to build muscle strength can be useful to increase your golf driving distance.