first let them dry well!What i do is plant them in a peat-perlite mix (lots of perlite!) and give them warmth;they are quick to germinate and if conditions are right youll have miniature prickly pears in about 3 months!(when i say miniature i mean finger-sized! lol)i dont use sand coz where i plant them is their permanent spot and my medium must have some nutritients!
I have no idea about strelitzia care though!
cheers

I ate som prickly pears and saved some seeds and they all germinated on top of a soil/perlite mix. i cleaned them from the pulp and left some overninght in a glass of orange juice. then I put them in a clear food container with the lid on but making sure there was a little opening... now after a few months they are like 3 ' tall.
I wonder if all the prickly pears are Opuntia ficus indica