Basically there are only six golf swing fundamentals that all golfers, whether you are a pro or a beginner, must know and follow.

The Grip

The grip is simply how you hold the club in your hand and there are three basic grips:

The Single Overlap Grip: This is where the pinky of your right hand (reverse for left-handers) overlaps the index finger of your left.

Interlock: This is the same as the single overlap grip with the exception that the pinky interlocks or wraps around the index finger.

The Baseball Grip: Pretty self-explanatory you hold the club like you would a baseball bat except you are swinging at a smaller ball and on a different angle. All ten fingers will be touching the grip

Any of these grips will do just fine as long as you pick one that you are comfortable with and keep practicing with only that one.

Posture

This is simply how you set up the ball, the width of your stance, knee flex, straightening of the back, bending from the hip and the angle you maintain throughout the swing. All of these are golf swing fundamentals:

Don't be afraid. It's really not as difficult as it sounds.

Width of your stance should be around shoulder width

Knee flex: Your knees should be slightly bent to allow a little bit of motion but used more like shock absorbers on a car.

Straighten the back: Your back should be straight at about an eighty degree angle.

Bend from the hips: Bend at the hips not the back.

The angle the back maintains: Try to keep the same angle that you started out with. If you change angles then everything changes.

Pivot
This is how you body moves from your head to your toes

Hands and Arms

Hand and arm relationship or better known as coordination is a very important step to learning the golf swing fundamentals.

Picking out a Target

Alignment is simply picking where you want the ball to go. For example, if you are trying to get to the green then make sure your body is facing the green when finished.

There is also a mental aspect in picking out your target. If you are more worried about the water hazard in front of you then guess where your ball is going to go, it is likely going for a swim. Try to look, focus on your main objective, ignore the hazards.

Mentality

Your mental attitude is probably ninety percent of the golf swing fundamentals.
You have to be able to play the game without thinking about all the above. That means you need to practice so your body does all the above naturally without you thinking about the next step.