Before doing any spellwork, I perform a ritual bath. My altar is always "set up" even when not in use, with a candlestick at the northern corner, a censer at the eastern corner, a bowl of salt water at the southern corner and several earth items at the western corner.
Importantly, the completely black bowl at the southern corner always contains salt water. The salt I use comes from Israel's Dead Sea. I only use one small chunk of salt per filling and change the water prior to shabbat or spellwork.