There are various things to do to an Earthenware pot before using it. It nears soaking, and then perhaps some garlic and oil on its base depending on the clay. This is to prevent thermal shock, also to allow the porous clay to keep things moist.
Some types of pot are soaked every time they are used, others just the first time. Some pots are tempered with milk. Others made with local clays may be soaked in rice water for a few days to remove impurities.
The key to this is recognising the clay, or having the sticker on it telling you what to do. It's surprising how many people buy these pots on holiday, then get home and find they never use them so they find their way to the charity shop, where I am more than happy to give something ideal for me a new home.
Here are my recent purchases and some different ways I seasoned them.