How to write the perfect paragraph

Each paragraph is part of a journey for the reader. The writer's job is to make sure the reader doesn't wander off. A good first step is to make sure the writer doesn't wander off. Each sentence in a paragraph should connect some way with the first sentence. Let's use the following as an example.
"There were many similarities in the lives of Abraham Lincoln and John F. Kennedy. Both were shot and killed. Lincoln was born in a log cabin of poor, uneducated parents. Kennedy was Catholic. Lincoln and Kennedy each had vice presidents named Johnson. Both men's political futures rose as the result of debates. Both were elected in years ending in '60. Lincoln's wife's name was Mary Todd while Kennedy married Jacqueline Bouvier. Lincoln's secretary's name was Kennedy while Kennedy's secretary's name was Lincoln. Kennedy had thick brown hair. Lincoln had a beard. Lincoln was shot in a theater while Kennedy's alleged assailant was captured in a theater."
Now let's eliminate every sentence that doesn't have some tie to the first sentence. Here is what we come up with:
"There were many similarities in the lives of Abraham Lincoln and John F. Kennedy. Both were shot and killed. Lincoln and Kennedy each had vice presidents name Johnson. Both men's political careers rose as the result of debates. Both were elected in years ending in '60. Lincoln's secretary's name was Kennedy while Kennedy's secretary's name was Lincoln. Lincoln was shot in a theater while Kennedy's alleged assailant was captured in a theater."
The second example is clear, concise and complete and it has a crispness to it, all because the writer stuck to the point.