Slice vanilla beans in half lengthwise to reveal inside of beans. Cut if needed to make them fit into your jar.
Place them in a tall glass jar.
Pour the alcohol of choice over the beans.
Cap tightly and shake gently.
Store in a cool, dark place for at least a month, shaking occasionally. I prefer to leave 2-3 months for best flavor.
Notes
I use my vanilla extract straight from the jar and just replenish the alcohol as I go. You can continue using the same vanilla beans until you notice the extract losing its flavor. If you need a sweeter vanilla extract for a recipe, just add a little raw honey or maple syrup for a corn-syrup and refined sugar free option.