for my cats, you have to make sure there are no clothes, towels, plastic bags, (anything really) on the floor, and the box has to be so clean you could eat out of it (nasty, sorry, but they really are picky about how clean it is). also if you dont feed them when they are used to it, or if their (your) schedule changes in any way they tend to freak and piss on something. they also really love to pee on things like rugs/carpet, so if you have all hardwoods like us it helps!
they also make this thing like a glade plug-in that puts out an odorless scent they can smell to help calm them and supposedly it helps. ive never tried it but its called feliway.
Feliway Spray For Cats
some people really believe in it but we havent had it get so bad that we need to try it. some cats are just so picky, they dont want used furniture that other cats have been on, or sweaty gym clothes on the floor, whatever.