Every coach has his or her own view on how to teach the forehand. Whether it's the grip, the footwork, the backswing, or the amount of wrist and spin used, it's impossible to reach agreement on the correct way to hit a forehand.
Of course, there's a very good reason for this; namely, there is no, single, "perfect" way to hit any tennis stroke. Sure, there are fundamentals that need to be in place, but what may be very effective and natural for you may feel totally awkward and foreign to the next player.
When teaching the forehand to beginners, it's a matter of what comes naturally for each individual. It's then the job of the coach to address and correct flaws in the stroke, while ensuring that the fundamentals are sound. Initially, keeping things as simple as possible is the way to go. Then let the stroke evolve.
Teaching a sophisticated, multi-segmented forehand from day one is like trying to teach algebra before the student has a grasp of simple mathematics.
However, when it comes to more advanced players, I must admit to having a personal preference for a semi-open stance, semi-Western grip, small to medium loop, fluent backswing, significant hip and shoulder rotation into the ball, and a laid-back wrist that explodes the racquet head from under the the ball for topspin or comes in directly behind the ball for a flatter shot. My all-time favorite player's forehand is Andre Agassi's.
Once again, though, I can't stress enough that there is a wide range of options with the forehand stroke. To help you become familiar with the options, below is a list of relevant terms as they apply to the forehand.
Set up position is side on to the net with the left foot stepping forward and into the ball. This is not the preferred footwork for today's tennis players as it severely limits hip and shoulder rotation, which equates to reduced power. A closed stance is effective on low mid-court balls, where an approach is played with a left foot to left foot forward "hop", which makes for a very effective transition to the net. This involves a highly advanced footwork technique that is very difficult for beginning and intermediate players.
Set up position is with the left and right foot directly in line with one another in a side on position to the net.
Set up position is with the right foot behind and outside the front left foot with the hips and shoulders rotated so that your opponent has a good view of the back of your left shoulder. Your feet should be approximately at a 45 degree angle to the net.
Fully Open Stance
Set up position is similar to the semi-open stance; however both feet are in line with one another standing square on to the net. Hips and shoulders are rotated as in the semi-open set up position.
It needs to be said that in the case of the semi-open and open stances, the rotation of the body means that the momentum of the right hip will necessitate that the right foot will come off the ground and swing around the body in the direction you've hit the ball, ending up in front of the left foot (which also has a tendency to come off the ground as well). During the rotation, keep your shoulders level and make sure your head stays stable.
Backswings vary from long, loopy high continuous backswings to straight back, extremely early, abbreviated backswings that break the stroke up into two very distinct movements. High backswings generate tremendous power, but I observe many of these tennis players have extreme difficulty when put under pressure, or if the shot requires any sort of improvisation. Some tennis players prefer to use their left hand to assist with the backswing (ensuring good shoulder turn), others prefer to use the left hand out in front of their body to assist with set-up balance.
Generally speaking, players like to follow through over their left shoulder. Some even like to wrap the racquet behind the neck. Others prefer to follow through slightly below shoulder level on the left side of the body. Some "catch" the tennis racquet with their left hand at the end of the follow through. As a general rule, the longer the follow through, the more length you'll get.
With specialist shots like a heavily topspun dipping passing shot, you might like to try a forehand stroke that comes sharply upwards imparting the necessary topspin, and then, after contact, the follow through comes sharply downwards, with the full stroke mimicking the flight path of the ball.
While the above is expressed in layman's terms, if you're looking for a highly technical analysis of the forehand stroke, you'll find all you want at Revolutionary Tennis. Just click on this forehand link.