Besides the serve, the topspin is the most important shot in tennis. A good topspin forehand will allow you to hit consistently with speed and depth, which will lead to a higher level of competitive play and consistency.
In practice, I have emphasized the unit turn, loading the racket by separating it from the non-grip hand, dropping the racket head, rotating the torso to contact, and following through in a circular motion as the racket extends. So far, we have not discussed extending to the target for consistency, more on that later.
FEELTENNIS.net is an excellent website that includes a blog post on the modern tennis forehand. I have known Tomaz for many years, and I can’t explain it any better than he does. I encourage our players to read and study his detailed post, then slowly develop and practice each part of the forehand.