If you really don't want your parents to know you smoke I'd be careful with the use of incense, axe, febreeze, and all that stuff. Fist off make sure to put it away because although it's not incriminating there is only one thing you'd be using it all for. Also if your room starts to smell strongly of all the cleaning products they'll know something is up too.

I'm just telling you that because although my parents never caught me I once left a fan by my window and my dad walked in the next morning and he instantly knew what was up.

If you want my advice just go outside or wait until your parents arn't home because if you keep it up long enough you're bound to get busted at some point.