Don't misunderstand what I'm going to say, Zumba Fitness is great, full stop. However, for those who are not so young, not so fit and/or have never learned dance steps before, the following may be helpful.
Firstly, if you can look in on a class run by a Zumba Instructor do, it will be an inspiration. I'll never forget the impression I had of Kay, flying sideways, co-ordinating head, arm and hip movements, all at same time. Fantastic! Unfortunately, this class had been running for 5 months and I knew I'd never be able to pick up the steps, so on April 1st I ordered my DVD set and have been practicing the Basic Workout for nearly 2 months.
The on-screen instructors first demonstrate the step they are about to teach and then break it down into three Easy Beat stages. Initially, I found the foot work was well taught in Easy Beats 1 and 2 but that working the arms and, to some extent, the hips was all thrown in at Easy Beat 3 with the thing going at full speed. It took me quite a while to pick up the arm and head movements in the second step taught. So, secondly, in the end I decided it was better to learn up the steps by watching the instructions repeatedly and then practicing from memory. I still do this even though the "whole body" instructions improve by the time you get to Cumbia and Reggaeton. This is fine. At home you're your own boss.
Thirdly, I would suggest adjusting the order in which you learn the steps. In the programme, 4 merengue steps are taught first. This is OK, but merengue is faster than salsa, which is presented third. The second set is of 3 quebradita steps and I really would recommend leaving these for later, say after Reggaeton. Quebradita Basic and Andole involve hopping and shoulder swiveling. It took me ages to get the balance right with the swiveling and both steps are energetic. I can just about manage quebradita andole now, albeit with my own version of the swiveling.
Fourthly, there's the music, particularly if you're practicing away from the screen. I bought Zumba Dance 2011 and found the heavy beat painful. The Rough Guides to Salsa and Merengue on the other hand are smashing and authentic. Salsa as I said before is slower than merengue. Last night I bebopped through my routine with Charlie Parker. At home, you can do whatever you want to. Slow the steps enough and it becomes a sort of Tai Chi.
The main thing is to do it at whatever level is right for you. Believe me, you'll breathe better, your joints will be looser, you'll be warmer. I practice on the kitchen tiles while I'm waiting for things to cook. I play whatever music I fancy or none. I wear loose clothing and a certain brand of comfort shoe. I'm 63 and have never learned a dance step before in my life.