Complete book of incense, oils and brews

One of the secrets of real magic is that it is controlled by the mind. The more things in your ritual to help your mind associate with your goal, the more powerful your ritual may be. Colored candles, scented oils, natural incenses, and more all add to the impact of the magic you wish to do. But how do you know which incense to burn? Is it possible to add scented oils together to get a more powerful oil? And how do you make your own, appropriately-scented tools?