Urmmmmmm, mas tricky. The problem with rooms close to the center of the house is ventilation. If smoke enters the ventilation system, it's possible for it to travel to other rooms. There is one bathroom in my apartment that if I smoke in, the whole apartment smells like weed in 2 minutes!!

For your situation, I would recommend this procedure:

1. Get a 'tea light' burner and some oil. 'April Rain' is an awsome light scent, gets rid of herb, and doesn't linger long.
2. Light said tea light and oil BEFORE smoking.
3. CLose room door and place towel at bottom of door.
4. Only open your window to vent if there is no danger of the smoke reentering the house...eg. it's not going to come back in through a different window.
5. By time you've done all that, smoke.
6. When you're done, let the tea light and oil burn for about 5 or 10 minutes more. If you're smoking a joint or blunt, you may need to let it burn even longer.

I've found that little method works best when using pipes. Pipes help to trap smoke and keep it from windering...as long as you don't forget to cap it. Joints and blunts produce heavier and denser smoke, much harder to get rid of the smell.

If you can, turn on any ventilation before you start smoking. Simple physics...air will travel the path of least resistance. Turning on the A/C will increase the air pressure in your home. When you open a window to vent, that smoke is going to pop right out b/c it is the best path with the least obstructions.

Good luck.