wearing a condom that is held on with a couple of cock-rings and filling it with pee. Stoking using the warm pee and then watching cum mixing with pee in the condom. I have actually videoed this play fun.
In the shower a lot. Soapy hand feels good and delivers a very intense orgasm. And cleanup is easy.
Out of the shower, best way is sprawled in a comfy chair or couch and massaging gently with some edging. Doesn't happen often anymore, though, due to circumstances.