The result will be a slightly ashy colored mixture—now that's real vanilla sugar!

Store it in an airtight container.  It should last you for ages.

Don't buy vanilla essence and don't buy ready made vanilla sugar. It's so expensive you don't get much and you can so easily make a much better version yourself. You should use vanilla pods. Although the pods are quite expensive, the recipe works out much cheaper in the long run because of the amount you can make.

Don't buy vanilla pods that are dry and hard—buy them fat, sticky and squashy. What we want to do is infuse the natural flavor of the vanilla pods into the sugar. It is perfectly fine, and obviously quicker, just to pop the pods in an airtight container with the sugar; you will achieve a subtler flavor. I really like this recipe though because you get the maximum flavor from the pods.

Source: www.recipeslive.com/dish-types/spices/vanilla-sugar-2.html