To begin with the choice of colors would top the list. So what family of colors is on your mane wish list? Are you looking to alter the color or color the gray?
Another thing that's changed from when your mom used to color her grays away under the cover of darkness is the quality of the products available. It's been a long time since anyone has gotten even a whiff of any strong, offensive smelling products in salons. Those have long since disappeared or been replaced by gentler formulations that are free, or mostly free from ammonia, peroxide or other harsher chemicals.