incense only gives away the fact that you are trying to cover a smell...
as does using cologne, perfume, or any other kind of artificial scent.
i when i was 15 or 16 (it's been quite some time since then) i would just do what i already told you to do before... OR ...burn some paper in the room. that'll cover the smell pretty well if you burn enough paper...(just a couple sheets) then you can just tell your parents that you're a firebug.