What new golfers need when they are starting out, more than anything else, is good quality golf lessons on golf, some basic advice, especially of the golf swing. The next essential element is quality practice. The game of golf is as much a mental game as it is a physical one, and both of these can be served well by practice, but only if it is done correctly. Instead of improving your golf swing, ineffective or incorrect practicing can ingrain faults into your swing and make your overall skill worse off.
We have two different types of memory, one where we consciously remember things in our brains and the other which is simply muscle memory, and like every other sport, golf relies heavily on muscle memory. Repetition is the key to muscle memory, the more often we do something physical the more automatic it becomes, our muscles begin to remember the precise movements we have been repeating. This is normally advantageous to us, learning to play a musical instrument would be impossible without it, those intricate fluid movements that are learned over time would, instead, be like our first attempts - all the time.
Muscle memory, however, causes as many problems as it solves. As far as the golf swing goes, it is a very technical series of physical movements, as easy as it looks, it is not easy to get right, the golf swing is difficult to master. If we practice when our golf swing is not producing the correct results then we are feeding our muscle memory the wrong information, our muscles don't know any better, they simply remember movements that we repeat over and over again. The correct way to practice the golf swing is to repeat the swing when it is right, when we have a good swing. If you are trying to correct a golf slice, then don't take another practice swing just after producing a slice or any other swing fault.
You often see too many golfers who, when they have played a bad shot, immediately take a practice swing or two, just think about that for a minute. What do you think is the outcome of practicing a bad shot? The more we repeat it the more our muscles remember it. It is clearly the wrong time to practice, the repetition of practice should be kept for when we have produced a good shot and not a bad one. Remember this one, it's really important, especially if you want to improve your golf swing.
Take your bad shots philosophically and just shrug them off, the more importance you give a bad shot in your mind, the more likely you are to produce one, repetition comes in all shapes and sizes, and worrying about a bad shot can be very repetitive, so try not to over-emphasize a bad shot in your mind and certainly, never practice one, it is a huge mistake and one that is easily avoided. Remember the old saying, "Be careful what you wish for?" Well, worrying about producing any particular swing fault is much the same as wishing for it to happen, your mind has a habit of trying to give you what you want.
There is a time to practice and a time to leave well alone, recognizing which is which is the key to understanding when practicing will be helpful and when it will be detrimental. It seems natural to practice a bad shot because we think that extra swing or two is correcting the swing fault, but this is the opposite to what is happening in reality. When we take those extra swings, invariably they are identical to the one that produced the bad shot in the first place.
So, when you have a good shot, practice what you did to achieve it, as often as you like and remember, if you have a bad shot, walk away from it, practicing then would be wrong. Also, bear in mind, this is just as true for more experienced golfers as it is for new golfers, keep your muscle memory for the good shots.