Welcome Calee!! I too am a "Cathe convert" from The Firm. I have been working out with Cathe since January of this year. I have seen amazing results from the short 6 months that I have been following Cathe's routines.
If you are familiar with step routines, Cathe's Low Max is a good one to start with. You can make it as easy or hard as you want it to be. It is an interval workout. It consists of 7 mini-step routines each followed by a "blast". It is an excellent cardio workout. When I first began with Cathe, I used my Firm step (the newer one that is longer) to do Cathe's step routines. It worked just fine, but was a bit too short for me to really get into the moves. Once I felt comfortable with her step routines, I invested in a full size step and risers, but the Firm step is fine to use if you do not have the full length type that Cathe uses. As far as strength routines go, Muscle Endurance or Power Hour are good ones to begin with for muscle endurance. I hope this information is helpful to you.
Again, welcome!!
Jenn