I do not believe there is any such thing as the perfect golf swing. You only have to look at Tiger Woods, if we all tried to copy his swing a lot of us could end up with damaged backs! Everybody has limits to their flexibility and should alter their own swing to suit their own capabilities. Having said that the mechanics of the swing can be split into the various parts and you can practice these different elements to improve your swing.
The Setup
The setup is a very important part in enabling you to hit a perfect golf shot. If you get the setup right you will consistently get back to the impact point with power and control. If you currently suspect your set up may be the cause of your bad shots, the good news is that this is certainly the easiest part of your swing to correct. Your feet should be approximately shoulder width apart, this can vary slightly depending on the length of the club you are going to use. But remember that a too wide stance will limit your ability to turn and too narrow will result in loss of balance. Remember when you address the ball to keep your back straight. It is vital that your spine is straight during your swing as this is your turning axle. Always bend from the hips when grounding your club behind the ball.
The Backswing
You need to keep your left arm straight(right handed players) throughout your backswing, but not rigid - you should never have any tension in your body as it can ruin your timing. Take the club back as far as you can comfortably turn , if you can only manage a half backswing that is really not a problem. Try not to rush, a slower tempo is usually far more effective.
The Downswing
It is very important with the downswing not to try and hit the ball as hard as you can . It should be a smooth controlled movement. A rushed downswing will ultimately result in very poor shots. Also one common fault is to only use your arms and wrists to hit the ball, you should always use your whole body, it will give you a lot more power and accuracy .
Impact
It is very important that you swing through the ball on impact do not swing at it. If you watch you will see that good players always let their hands lead the clubhead through impact, where as your average golfers allow the clubhead to pass their front arm before impact.
Follow Through
Your swing does not end after you have struck the ball - it is crucial that you complete your swing . It is a fact that over 80% of amateurs have very little follow through in their golf swing. It is such a neglected part of the golf swing, just a little attention to this will see great results.
So next time you are at the practice range take a look at these different areas of your swing and see if you can make improvements. It is good practice to have golf swing drills that you work through at the range, but you need to remember that when you take your swing onto the golf course it is not advisable to have mechanical swing thoughts or swing thoughts that relate to only one part of your swing. Once you are on the course your main focus must be your target. Get a picture in your mind of the shot you are going to hit and trust your swing.