In this post I'll talk about some of the things I do with my general fitness clients. Training a lot it condo gyms, I see a lot of craziness, and the worst of it is usually from the other personal trainers. I see one trainer fairly regularly have a middle-aged woman do every isolation exercise imaginable on a cable cross-over. Most people just need to learn to move.
My clients' programs consist of primarily big basic strength movements: Squats, deadlifts, presses, rows, pull-ups/downs. I prefer static holds for core work (Planks, bridges). I also do quite a bit of mobility work. Which exercises, and how much depends on the client, but most of my clients work desk jobs, so we focus on hip and spine mobility.
I generally don't go as heavy with clients as I do in my own training, since most are fairly new at strength training. But I don't go crazy with rep numbers either. Presses (upper and lower body) I generally stay with 5 reps for work sets. For upper body pulling I'll go higher (8-12) and use peak contraction holds. Going too high with reps just turns the exercise into cardio, and it makes it hard to maintain proper form, especially with challenging weights. I want my clients to get stronger, not weak and injured. While I'm not trying to make strongmen or powerlifters out of my clients, I find that getting them stronger on big, basic movements will fix a lot of things.
So, to sum up. If you're just getting into weight training, no matter what your end goal is, you need to focus on mobility, core stability and strength. Once a solid foundation is laid, then you can worry about getting huge, or getting shredded.