It’s believed in Celtic and Gaelic tradition that the veil between the living world and spirit world is thinnest at Samhain, which is why divination became so popular at this period of the year. I’ve heard of this particular method used in my family line in the past.
Fill a bowl with water. The bowl should be deep and wide enough to allow candle wax drippings to take shape. Putting the bowl in the freezer for a few minutes will help but don’t let the water solidify into ice.
Take the bowl of water and your candles to your altar or a place in your home where you can work comfortably in peace. Hearth witches or kitchen witches might consider working in the kitchen. Garden witches might consider working in the garden. That sort of thing. In my family tradition, environment mattered to the success of the divination. Working at night is best too.
Candles work best when made of natural materials but should at the very least produce a decent amount of drippiness. I generally use white candles since white is an easy substitute if you don’t have desired colors. You may coordinate the color to the subject of your divination question if you choose–green for money, red for love, etc.–but it’s not totally necessary. Our ancestors doing this particular divination method didn’t have easy access to colored candles like we do. They used beeswax, tallow, etc.
Light the candle and let it warm up pretty good. I have better luck with pillars than tapers but it’s just a matter of personal preference. While you wait for the flame to do its work, concentrate on your question. When the wax gets melted enough, ask your question aloud and then pour the drippings from the candle into the bowl. The cold water will make it harden fast.
Study the shape of the melted wax in the water. This is where you’ll need interpretation skills. I’ve been doing it for a long time and I never had a key for deciphering shapes in the wax but there are some suggestions online if you’re new at it.