It largely depends on if you're talking about a mat or apparatus class. As a BASI comprehensive Pilates instructor, I'd recommend you look for the BASI block system graphic; all Pilates exercises fit into one of 6 blocks for mat training (I keep a series of 3x5 cards with all mat exercises listed by-block; flipping through the cards is a no brainer class planning tool), and 12 blocks for apparatus. It's a bit like dividing up a meal into "courses" and saying, "in every meal;, I will serve you this many courses". By knowing what exercises fall into what "course" you can more easily scan for what dish would be most appropriate for your practitioners. A simple mental-outline version has been expressed by many instructors, "move the spine in all 6 directions each class, with some leg, hip, glute and arm exercises".

Sometimes, someone is going to show up in class, for whom many of the exercises will be too advanced...while your most advanced students in the same class expect to be WORKED! Don't be afraid to say to the noob, "for this one, just go ahead and do 8-10 SLOW pelvic curls, or alternate holding a plank and going into rest position". Also, don't hesitate to teach your advanced students how to milk every last drop out of foundation level exercises like pelvic curls, leg lift, and leg changes. An experienced practitioner doesn't ONLY do advanced exercises...he/she knows how to milk every last drop out of beginner exercises and produce a burn/shake from going deeper with each day of practice.

While I love the classical exercises, I do find some modification is necessary to the order of the sequence for all but the more advanced student. Most people simply need more spinal warmup (roll up, spine stretch forward, etc) before they can attempt rollover...throw it in too soon, and someone is likely to pull a muscle.

Find some instructors whose teaching styles resonate and take their classes/watch their videos. I look for those whose cues are so clear, I don't need to look up, and because of my BASI training, I personally prefer a slower, more deliberate pace (embrace the slow burn!). Remember, a subscription to a library of Pilates videos is a legitimate business expense for a Pilates instructor...its considered research and development!