No. For the person who endeavors to take on CrossFit without the guidance of a certified CrossFit trainer, we recommend three distinct approaches, depending on your fitness experience and available facilities:
1) If you are largely familiar with the stable of CrossFit exercises then start with the WOD (Workout of the Day). If you've had exposure to Olympic weightlifting, powerlifting, and gymnastics, jump right in. If an exercise is unfamiliar, acquaint yourself with the movement through the video clip for the movement on the exercises section of the site. This option is for those athletes with an extensive experience in athletic strength and conditioning - jump right in.
2) If some or many of the exercises are unfamiliar to you and you are only modestly acquainted with elite athletic training,we recommend that you follow the WOD and substitute other exercises for those where you don't have either the equipment or skill and then devise a plan for acquisition of the necessary skills or equipment needed to participate completely. We are developing a Substitution Chart in the FAQ for replacing exercises for which you've not developed the skills or don't have the equipment.
3) If many or most of the exercises are relatively or completely unknown to you, then we recommend that you begin learning the movements for a month or two until you can either perform our common exercises or have substitutions worked out for those movements under development. This is a great place to begin for anyone with little or no experience with serious weightlifting or gymnastics.
CrossFit is a "minimalist program" and this is reflected by the functionality and limited number of our exercises and the simplicity of the equipment we use compared to most commercial gyms.
In any case it must be understood that the CrossFit workouts are extremely demanding and will tax the capacities of even the world's best athletes. You would be well advised to take on the WOD carefully, cautiously, and work first towards completing the workouts comfortably and consistently before "throwing" yourself at them 100%. The best results have come for those who've "gone through the motions" of the WOD by reducing recommended loads, reps, and sets while not endeavoring towards impressive times for a month before turning up the heat. We counsel you to establish consistency with the WOD before maximizing intensity.