If you are going to play more jamaica ska style, cup mutes are sometimes used, as well as harmon mutes. But if you listen to ska you won`t hear a lot of mutes, if any.
I don`t play with mutes in ska anyway, but I play more uptempo ska with also a tenor sax and a trombone player, so if I use mutes the others should play softer too.
If you play a solo it could be nice, but that depends on the style.
Check out our site, so you can hear some ska. It is in dutch, so you probably won`t understand what we sing
www.j-stars.nl
Good luck, ska is the best!