The most common mistake I see with top spin is the assumption that more follow requires a harder stroke. It may appear a logical assumption, but good follow requires more spin, not just more speed, and more spin is achieved with a higher hit on the cueball, not just a harder stroke. The illustrated practice shot requires a hit on the cueball as shown above. It requires a firm, confident stoke. Since a little left spin is applied, the object ball will throw right, which means the cue must hit the object ball a hair to the right of the spot you would normally aim at if no english was being applied.
Every shot requires practice and adjustments.
Different tips and shafts produce more or less spin and throw. All illustrated lessons will require adjustments to the hit to compensate for the differences in equipment. It is the theory that needs practice, not the illustration itself. This same hit on the cueball is useful in a wide variety of other situations. I like the one shown in the illustration because it will force the shooter to develop good follow.