Here is the basic set up for a scorpion, however, my terrarium is large compared to most housing a single invertebrate.
Due to the varying species of scorpions, it is best for you to research the long-term care of your specific species. If you own Australian species of scorpion, I'd advise you to look at "http://www.thegreenscorpion.com.au/showconcats.toy?cnid=44056" with regards to long-term care. Hwever, no matter the species, the caresheets on the website will provide useful information.
Step 1: Buy the stuff
The things you need are:
1) A tank (terrarium or fish tank with a sealable lid with vents)
2) Sand or other substrate such as Coco-Peat (must be clean, try your local pet shop or online)
3) Leaves, bark, small sticks, rocks (anything a scorpion can hide under or climb on but ensure they are clean)
4) A very small dish
5) Cotton wool
6) Crickets or cockroaches (food)
7) Your scorpion(s)
You will also need a terrarium heater light to heat the tank and provide UV light to the scorion.
P.S Small scorpions can climb on glass, so if you get small scorpions make sure you get a tararium that is "escape" proof