When preparing to attack a defense the most important thing to do is to understand the nature of the defense. Every defense has strengths and weaknesses that are built into its structure.
Looking at a defense can be overwhelming. The first time you go to plan out a game many offensive coordinators will spend hours pouring over the film without really taking away any solid pieces of information. Instead it’s critical to find a systematic way to process game film so that you can come up with a great game plan in the limited amount of time you have.
The first time you look at a defense you need to look for the overall structure of the defense. Is the defense an odd front or an even? Does it tend to keep two safeties back or does it roll one to the field? How do they handle shifts and motions?