Times i've gotten caught...
1. Never smoke joints in your room. i dont care if your blowing it out the window and spraying and burnin incense. The burnt paper mixed with weed reeks your whole house!

2. After smoking outside a few times, i always learn to bring a jacket or hoodie to get rid of the smell. The smell gets all over my clothes, and if i come home wearing a hoodie they dont notice. or smoke with a hoodie on, then take it off. But beware they may ask "Why are you wearing a jacket? its not cold out?" But they wont catch on.

3.Do NOT let your friends see your parents. My friends were fucked up one time, i was getting picked up at a friends house and they came running out trippin on shrooms and yellin at my mom.

Thats all i can think of. Good Luck and dont go paranoid!