I tell the history of my cake decorating skills in a reply to @hebrewhousewife's similar question...

As far as practice though, you know, I guess I really don't practice at all? But I have spent hours and hours and hours practicing my artistic skills, drawing and painting and so on, which I'm sure gives me a huge boost. I've never tried sculpting much, but I know I can visualize things in a three-dimensional space quite well too. Add to that the manual dexterity that a decade of music lessons can give you, and it just all seems to come together!!

So, maybe I was born with some raw talent, but a lot of other factors have helped me to be good at it :)