Tennis is a complex sport. If I were to simplify how to teach a beginner how to hit the ball from the baseline, this is where I would start:
First, practice watching the ball from the opponent's point of contact all the way past your own point of contact. Determine whether it is a forehand or backhand, and turn your shoulders before starting to move your feet to the ball. Make sure to recover and move back towards the open part of the court. Repeat this same idea until someone misses a shot or hits a winner.
Next, I would make sure the player understands that tennis is a game of repetition. Regardless of how the ball is hit to you, the goal should be to try to similarly swing at the ball each time. This is much more difficult than it sounds since almost every ball is hit with a different speed, direction, height and depth—not to mention the different spins a player may hit. Also, there will be many times a player must hit the ball while they are moving, which complicates the idea even more.
In summary, watch the ball, turn once you know it is a forehand or a backhand, take a few steps to get your position comfortably, swing the same way each time, recover and keep repeating this process until the ball is no longer in play. This simplification will be greatly beneficial to beginners as well as players at the highest level.