One important fundamental that should not be ignored is your alignment. Unfortunately, alignment is one that sometimes has a tendency to waiver. This is exactly why it is crucial to keep a close eye on your alignment and to use aids as much as possible in your practice. If your eyes are looking at the target, but your body or club face are actually aligned left, the golf ball will not start on its intended target line. This is why poor alignment leads to swing problems. It could cause a number of compensating problems in your swing including changing your path and plane to get the ball starting back on the intended line.
If the club face is a degree open or closed to the intented target line at impact, it can cause a miss of 10-15 yards. This is quite substantial and could easily be the difference between hitting the green or ending up in a greenside bunker. This is the difference between making par or bogey. If you attend a PGA Tour event and visit the driving range, you'll notice that a majority of touring pros use alignment sticks in their weekly preparation to ensure that their alignment is spot on prior to each round. So why aren't we using alignment sticks in our practice and preparation?
To have proper alignment, your feet, knees, hips and shoulders need to be aligned parallel left to your intended target line. Finding an intermediary target 6 to 12 inches in front of the ball that is in line with your taget can help tremendously on the golf course during a round. It's a lot easier to find your target line just a foot in front of you instead of trying to line up with a target 215 yards away. This can be a discolored blade of grass or something that is easy to identify once you get into your address position. Lastly, get yourself an alignment stick or start using a golf club when you are on the driving range hitting balls prior to a round or when you're just working on your swing. Having proper alignment will save you several shots per round.