These are all good but the one thing they all have in common is the enevitable fact that it will smell like pot for a short time. The method I use, you can smoke in the room without using a fan or a window (though it works better with them) and not even smell smoke.

What I do is I get one of those really small one hitters right? Then what I do is light it up and just as I am about to stop I quickly put the lighter over the top as to cover the entire tiny bowl. Now keep in mind as I am placing the lighter on the one hitter I am still breathing in. This is very important because if you stop inhaling and do this excess smoke will come out. I then grab my thumb and cover the other side where I put my mouth on. I hold it in for as long as I can, usually for me its about 40 to 60 seconds. Then I grab a spoof and blow through that. By doing this all of excess smoke within the one hitter fails to escape and by holding it in for that long little if no smoke comes back out but just in case a little does you have the spoof to back you up. Oh yeah and don't forget to take in the excess smoke that's trapped in the one hitter.

This can work without opening a window or using a fan but for extra measures I usually cover up the bottom part of the door and have a window open with a window fan blowing outside. When I use this technique I usually also go to the window and cover myself in the curtains where the fan is at. Also make sure and have something to cover your breath, your hands, and eyes because those are the obvious places to search when suspecting a pothead. My advice would be to put eye drops in before smoking so you don't forget which I always do. And then after you smoke use a hand sanitizer to wipe off the potential ash that could have gotten smeared on your hands and to get rid of the pot smell. Also have some gum handy for the breath and just for extra extra measures use fabreez to cover up any other smells. Never use axe or something because it would be weird to your roomates if they smelled that all the time. At least with fabreez you can justify using it to make your room smell better. No one uses axe to make they're room smell better. Its always for body oder.

Anyway hope that helps.

Edit:

oops lol I misinterrpreted the topic. I thought you didn't want these people to find out you smoked. I took a lot of thought into it anyway so I'll keep it.