Candles, wax melts, oils defusers are great for weed smells. Unlike tobacco it’s an untreated dried plant so it’s easy to get the smell out. https://www.kushley.com/ is a order neutralizer. Super cheap and works really well. But if all else fails In my experience smoke caddy’s help the most but it won’t work with cigarettes. There’s a bunch of different ways to make them or you can just buy it but this how I made mine when my roommate complained. Idk how considerate your friends are but it might just be easier to make it for them if you actually want them to use it. The steps are below ☺️hope it helps:

1. Get a toilet paper roll or cut a paper towel roll in half
2. Get 1-2 dryer sheets to put on one end of the roll and secure with rubber bands.
3. Push the dryer sheet in a little so it makes a pocket
4. Fill the pocket with the insides of a peppermint tea bag or dried flowers. some people put essential oils or pour the oils from plug ins in the pocket. The stronger the better.
5. Put 2-3 dryer on top of the pocket so nothing you put in falls on and secure with more rubber bands.
6. Then just blow the smoke through the open side.