Common sense is your best friend here.  The best place to consume any type of illegal substance is in your own home.  If a police officer comes to your door and asks whether he can come in, you should politely decline to allow him into your house.  If he does not have a search warrant, he cannot come in.  

An officer is allowed to walk up your front steps and knock on your door, just as a neighbor or anyone else can do.  Anything an officer sees from that vantage point is fair game, so don’t keep any drugs or paraphernalia in a place where they can be seen from the front porch.

The law makes a “bright line” distinction between your rights inside your home and your rights outside your home or in your car.  By far the most common way to get busted for drug possession is to get pulled over for a traffic infraction with drugs in the car.  To avoid this, keep the drugs at home.  But if you have to roll with them, buckle your seat belt, use your turn signal, and drive the speed limit.  If you are pulled over with drugs in the car, don’t answer any questions or admit to possession or use of the drugs.  Don’t consent to a search of the vehicle.  Ask to speak to an attorney.

Most importantly, Washington law severely punishes drug crimes committed with firearms.  Make sure to keep all firearms safely locked and stored separately from any illegal substances.  Never travel in a vehicle with a firearm and an illegal substance.