Biggest issue I ever had was over watering. But we were in CA at the time which most of my succulents had thrived. I have not had much luck with plants since moving to Texas. Maybe I am just lazy. Most succulents are pretty hardy, but can be establish, they don't really do well with transplating and moving in my experience. I always let mine dry out real good before watering, espeically while small, if they get to much water weight,it will stress the roots.
I miss my succulent garden, especially aloes. Some may be slow growing and some just take off, from the same type. Good luck.