I would recommend going in order that the DVD's were produced. The Classic's and Cardio Hits are one of the earliest DVD's I could find on Cathe.com. I have both of these DVD's. I have a lot more than these but haven't tried them all. The Classic's ( Step Heat 1995, Step Jam, 1996, and Step Max, 1995) and Cardio Hits( Power Max, 1996, Step fit, 1997, and Step Works, 1998) both have three step work outs on each of them. These all have choreography that is usually easy to follow, although did have a problem with power max and the 360, or is it 180?, move. Anyway, that is the only problem I've had with these DVD's, but I haven't done Step Fit or Step Works yet. In these older ones, Cathe introduces moves that she uses in her newer DVD's and she repeats most of the moves a lot. The other good thing about these older ones is that your heart rate will do o.k. Cardio Vascular wise they are around the intermediate level with the step moves being for a beginner/intermediate. That is my opinion anyway.
I also have Low Max and I love it. I did have trouble with a move here and there, but after a viewing and rewinding several times, I got it o.k. I have Cardio and Weights and while I don't do the weights part, the cardio part is pretty good. It is only 30 minutes but you'll get a pretty good heart rate.
Something that helped me learn moves is that when I'm trying to learn a new workout, I don't try to workout with it. Let me explain. I do a cardio workout (I do most of my workouts at the gym and I do a lot of weights at the gym so I don't do any weights at home. So I haven't tried any of Cathe's weight workouts. I just really love doing Step Aerobics to Cathe's DVD's, which is why I do them at home sometimes.) that I already know and after it is done, I will do one or more section of the new one. When I'm doing the new one, I am not worried about keeping my heart rate up because I've already worked out. Therefore, I am not bothered by having to rewind and try a move again. You can also move the DVD forward frame by frame and see exactly where Cathe's feet land. Another thing I learned from IMAX 2 is that it helps to sometimes watch one of the ladies behind Cathe. The reason being is that Cathe is wearing long black exercise pants and the others are wearing shorts. It is easier to see what each individual bare leg are doing that the black pants.
Just keep trying. If I can do it, anybody can.