The Secret Service has well defined procedures for protecting the President and any other person they are responsible for. Little was done according to proscribed processes on November 22, 1963.

Beyond the motorcade itself, there is generally a review of buildings along the route making sure windows were closed and a general elimination of threats along the way. When it come to the motorcade, the sequence of the vehicles and the protection provided was substandard.

Usually the the media truck would be ahead of the President's car, but it was placed much further back in line where it would not obstruct the shooters line of sight and they could not provide a visual evidence of the killing.

Motorcycles usually ride ahead and along side the limousine. If they had been in place there would have been obstructions for the shooters. Other obstructions would would have been Secret Service agents riding on retractable platforms on the Lincoln along with two more who would have been riding in the back platforms. The platforms were retracted and there were no agents protecting the President.

The driver of the car, agent Bill Greer, hit the brakes when the first shot was heard, rather than hitting the gas. Greer replaced the regular driver, Thomas Shipman, who passed away in his sleep at retreat at Camp David, a month before the Dallas trip.

After the assassination the Secret Service took possession of the President's body and the Lincoln limousine. They instructed the hospital personnel not to talk about what they had seen.  For some reason, Secret Service records of the trip have been destroyed.

Stories of individual agents and their actions in Dallas can be found here.

Honest Answers about the Murder of President John F. Kennedy: A New Look at the JFK Assassination
by Vincent Michael Palamara

Thousands of books and articles have been written about the murder of JFK, many of which are large in volume and short on facts. Quite often, these works try to reinvent the wheel, attempting to cover every single area of the assassination, as well as many tangential and unessential points, as well. The reader is often left exhausted and confused. The sheer volume of pages, conflicting facts, and theories leaves one unsatisfied and, quite frankly, not sure exactly what did happen on 11/22/63. This book seeks to separate the wheat from the chaff. It is 55-plus years later: it is time for real, honest answers in an easy-to-read and understand format. Proof of a conspiracy; no theories; to-the-point; a perspective on the assassination for the millennial age and beyond. Based on years—decades—of primary source research and having read countless books on the subject.

More by Vince Palamara.

Killing Kennedy: Exposing the Plot, the Cover-Up, and the Consequences
by Jack Roth

In Killing Kennedy: Exposing the Plot, the Cover-Up, and the Consequences, author Jack Roth interviews researchers, scholars, eyewitnesses, and family members of those who were part of the tangled web of US intelligence operations associated with the Cold War and the circumstances surrounding the assassination of John F. Kennedy. The author asks important questions, including why the assassination still matters today and what the lasting ripple effects have been since that fateful day.
 
The Kennedy assassination represents one of the most impactful events in not only American but also world history, and this book represents an important addendum to understanding its enduring significance. On November 22, 1963, the duly elected president of the United States was murdered in cold blood, forever destroying “Camelot” and national optimism for world peace.
 
Gleaning a “people’s history” of the assassination through dozens of insightful and heartfelt interviews, Roth presents a riveting narrative by creating a respectful, well-crafted, and emotionally charged book from which both older and younger generations will gain a greater understanding of our nation’s history and current status in the modern world.