I'm new to this as well. Prior to last April, I exercised haphazardly and didn't know what a "rotation" was.
I use Cathe's following explanation for STS as my guide to creating my own rotations:
MESOCYCLE #1 - Muscle Endurance (60% to 70% of 1RM)… In this phase the workouts will feel similar in nature (yet totally different format) to our other muscle endurance type workouts...working with higher reps ( 15 reps or more)....Here is where we burn calories, develop muscular endurance for long term activities, build stamina, and condition the joints, tissues, tendons for the next phase.
MESOCYCLE #2 Hypertrophy (70% to 80% of 1RM)...here is where we build LEAN muscle mass, break plateus, define our muscles, stimulate our metabolism....
MESOCYCLE # 3....Strength (80% to 90% of 1RM)…here you will do the least reps of all (6reps to 8 reps)…and really challenge the muscle to get stronger. Your body will burn more total fat, even at rest, because you have now increased your lean muscle mass, especially in Meso #2, and overall strength.
I haven't figured out my 1RM ~ I just go with whatever I can lift for the prescribed reps (so...for a muscle endurance rotation, I use a weight that I can lift relatively well for 15 reps, for strength, I pick something super heavy that only lets me eek out 6 - 8 reps)
Someone once asked here on the forum how to categorize Cathe's weight DVDs in regards to STS cycles, and this was the answer:
Meso 1: CTX, Muscle Endurance, Leaner legs, Power Hour, Legs & Glutes, Supersets & Push Pull
Meso 2: MIS, Pyramids, Pure Strength, Muscle Max, Gym Styles
Meso 3: Slow and Heavy and 4DS
*I like to use the Pyramids during an endurance rotation, before I start Gym Styles.
I think doing an endurance rotation has helped keep me from injuring myself. This is my first year with serious weight training, and I believe my joints appreciate the heads up before I go heavier in a rotation.
I can't say I've seen great definition or anything ~ I suspect I'm one of those who takes a while to see muscle. Grrr. But I feel great, I haven't hurt anything weight training, I've made strength gains (this may sound weenie to some, but I started bicep work with 5, 7 and 8 lb dumbbells, and I now use 8, 10 and 12 lbs), and I've lost some extra padding.