I started out with Weight Watchers and lost 99 pounds. Then I used a program called physiquetransformation.com and lost another 24. It taught me how to eat properly. I am still using it to stay on track, although I don't need it all the time. I just use it once or twice a week to make sure I'm not lying to myself.
I had some medical/medication issues a few years ago and gained back about 80 pounds. Now I'm finally losing again. I've lost 20 and feel really good this time.
For exercise, I started by riding my bicycle, a few blocks at first, then a mile, two miles, ten twenty, thirty, forty. Very gradually, though. A little more each day. When I began lifting, I used Kathy Smith with no weight at all, just the movements. Then I added weight. I moved up to The Firm but didn't like the multiple movements. I found Cathe and it was love at first sight. I've used Cathe almost exclusively ever since, although I continue to ride my bicycle to and from work (7 miles each way).
Progress is very slow and not at all steady, but what's the alternative? I feel better when I eat right and exercise, whether the progress "shows" or not. So I keep going. It's just like they say on the Firm vids: "Consistency is the key to results." They got that right. Just keep doing the right thing one meal after the other, one day after the other, etc. It all adds up, no matter which way you go.
Shari
P.S. I forgot that you also asked which Cathe videos were most helpful. I used all of her strength videos up to this last series. I haven't purchased the newest series, but I probably will someday. Eventually, I didn't even have to modify, although I did at first. I was never able to keep up with Cathe cardio, so I used Christi Taylor for step, P90X, and my bicycle.