I don't bother masking anymore really. If I'm paranoid I'll spray some axe. I smoke in my room at night (well not currently) and so I leave my window open to let it air out. Since I don't expect my parents to be coming into my room anyway, I usually don't try to mask the smell.

I used to burn incense, but I ran out. Plus, my mom always claimed to smell cigarettes (I NEVER smoked cigs) when I burned incense, and she would SWEAR it wasn't the incense she was smelling.

On the occasion I smoke when my parents are gonna be home soon, I will put on some deodorant (not too strong, just some old spice) and eat some food, like BBQ chips so that the scent of BBQ chips fills the air!