Mix 1 part of fragrance oil and 2 parts DPG (dipropylene glycol). Mix well. Do not use the fragrance un-cut or else your incense will smoke more than it should.
Soak incense in fragrance mixture for 24 hours. I find laying the sticks flat in a containers means I can reduce the amount of liquid needed to cover the sticks. (Try making a container out of tinfoil).
After soaking pour unused fragrance back into an HDPE bottle and mark (you can re-use this oil later for more incense sticks/cones).
Lay the cones or sticks out on a drying rack (baking rack) or hang in bundles with paper towels underneath to catch dripping fragrance.
Be sure to let sticks dry completely! (If damp the fragrance oil can eat through plastic). Do not try to speed up the process.