There is a simple rule in lighting incense as an offering for the Buddhas or Bodhisattvas. Treat the incense as something for the Buddha or Bodhisattva, so do not smell its fragrance. When holding it, and incense has a wooden stick at the bottom, then do not hold or touch the incense, simple hold the wooden part.
Never ever offer incense that has fallen off the floor.
Following these simple rules will show your respect to the Buddha or Bodhisattva and it will increase the merit of the act.