Always make sure you have one extra box than you have cats. If you have 3 cats, have 4 litter boxes!
Our cats all have decent sized mats under their boxes so they have somewhere to wipe their feet when they are finished tackling their business inside. We also use covered litter boxes (like little caves) but ensure the door is removed each time we buy a new one. Our cats love their privacy, but they also enjoy breathing 😉