Personally, I like to do ABC, ABC, DEF, DEF, etc. This gives me enough rest in between exercises to keep the muscle stressed but ready for another set. I try to structure the exercises as Legs Chest, Back or Shoulders, Tris, and Bis.

A: Legs - Squats
B: Chest - Pushups/DB Presses
C: Back - One Arm Bent over Rows

D: Legs - Lunge
E: Chest - DB Flies
F: Back - Pull Ups

Maybe do a super set here GH, GH, IJ, IJ

G: Shoulders - Overhead Presses
H: Legs Deadlift (SL RDL)

I: Triceps - Scull crushers/Tricep Extensions
J: Biceps - Curls

K: Calf Raises
L: Upright Rows (or many lateral raises, front raises, rear raises)
M: Sit Ups (or planks/side planks)

In your case, you have "Squats" and "Leg Press". In my mind these are basically the same exercise. I like that you added dead lifts. I would drop "Leg Press" and keep deadlift. I'm also not sure about Bent over rows AND Seated Rows? Are these basically the same exercise? I added pull ups and chest flies. I think pull ups/lat pull downs are a must do exercise. Chest flies isn't a must do but it's another chest. You might consider DB pullovers instead of chest flies.

Overall, you have a great workout and set of exercises. Keep working!

This is the whole routine, which I took from a book written by The Firm exercise DVD instructors.

I use the heaviest weight I can. I do 3 sets @ 12 reps. I struggled to do the whole circuit in a row three times. But when I did AB 3X, CD 3X, etc. I was able to complete it 3X. It was just easier I guess, not having to change positions with each exercise.

What would be a better format for these? To the PP, you're suggestion is to pair A/upper body and B/lower body?

Thank you.

A Sit Ups
B Push Ups
C Squats
D Curtsy Lunges
E Bent over row (back exercise)
F Dead lifts (I added this exercise for hamstrings)
G Overhead Press or Arnold Press
H Upright Row
I Biceps Curl
J French Press
K Seated Row
L Calf Lift (Using a 2x4 and a step up box)
M Leg Press (Using a step up box)

Space out lower and upper body, end with abs and go straight into stretch.

E is Arnold presses with dumbbells
C is squats with dumbbells
B is push ups
D is curtsy lunges with dumbbells
A is sit ups

I was challenged trying to complete 3 sets @ 12 reps of 12 exercises in a circuit. I would do A, B, C, D, etc. @12 reps. Then I would do A, B, C, D, etc. @ 12 reps, and repeat for a total of 3x for the complete 12 exercise circuit.

I changed it to complete AB AB AB @ 12 reps, CD CD CD @ reps, and so on, until I complete all 12 exercises.

Do you have a favorite or preferred method for how you complete the exercises in a circuit?

A is sit ups
B is push ups
C is squats with dumbbells
D is curtsy lunges with dumbbells
E is Arnold presses with dumbbells
and more