Over the course of the past couple of days there has been a fair deal of talk on the subject of using incense for magickal means. This was first instigated by P. Dunn over at "Postmodern Magick", and subsequently continued by my colleague Michael at the "Your Friendly Neighborhood Occultist" blog. I feel as though this topic is important enough that it warrants further discussion.
As Patrick and Michael have noted in their respective blogs, incense is a fairly simplistic offering that, along with regular offerings, tends to be ignored. Its importance really cannot be overstated, seeing as how it is, very literally, an energy source for the spirits we work with. Should we fail to give our ephemeral cohorts their due, we are doing them a disservice.
To that end, I'd recommend procuring several different types of incense, be they sticks, sprinkling powder, or solid wood, and burning them during the course of your rituals. Over time you will get a feel for the energies brought into the room by the burning offerings, which will then allow you to figure out which spheres the energy is tied to. Once you know this, you can figure out a personal system of correspondences and act accordingly.
Or, if you should desire to utilize an existing reference, you could always turn to texts like Liber 777.
Whichever methodology you choose, I'd recommend utilizing incense as a tool in your workings. Once you figure out how to do it, you'll be surprised at the role it plays.