How to set default shipping method

> I've just added some additional shipping methods. I'd like the
> default to be UPS Ground.

To sort shipping methods as you want, please set Pos. field in Shipping methods. Everything is sorted by this filed. If you want UPS Ground to be listed in front of UPS 2nd Day Air, set UPS Ground to 10 and UPS 2nd Day Air to 20 (or to 1 and 2). First one will be default.