How to I paint outdoor ceramic?

Not sure what it is you want to paint but there are several spray paint varieties that would work for many projects outdoors.

id use enamel folk art paints by plaid made for ceramic glass and mirror

Are you detail painting or just overall object painting? it'll make a huge difference...detail painting of statuary can be done with enamel based paints that will 'self -seal' & will last a few years before needing to be re-painted. IF you are looking at doing a light to dark gray or even a white/pearl look of a statuary figure [no details], then a base primer with the final color over the top of the primer will work [I'd do at least 2 coats of the final to make sure it is well coated].

Marine paint. Hope this helps.