This plant is in a 14cm nursery pot.
Light:
These prefer a well lit area, ideally close to a window while also not receiving any direct sun.
They won't tolerate darker areas too well so make sure they're getting adequate light year round.
Watering:
These plants tolerate being dry fairly well. Wait until the top 5cm of soil has completely dried out before giving a thorough drenching. If unsure, always leave it for a few more days as they will not like being overwatered.
Humdity:
They will thrive in a warm and humid condition, but will tolerate drier conditions without too much fuss. Don't mist these plants as they are techically a cacti and water becoming stuck around the leaves could lead to rot.