This is a very easy Febreze alternative - I've seen a ton of recipes using fabric softener... but those aren't very "green".
What you'll need:
a small spray bottle
1/2 cup rubbing alcohol or vodka
1 cup water
Fill the spray bottle with 1 cup water and 1/2 cup rubbing alcohol or vodka.
You'll now add the essential oils - I typically start with 30 drops and then work my way up. You can also mix oils to create custom scents. I also like using The Body Shop home fragrance oils in this mix and I've had no problems with them.
Note that you will be able to smell the alcohol, but only for a minute or so... after that things will just smell lovely. Rubbing alcohol has a stronger smell than vodka! :)
I use this on my couch, bed, curtains, dog bed, towels, etc. and the smell lingers for quite a while - for example, I sprayed my couch while cleaning yesterday and it still smells nice.