Well, it depends on what do you want it for. I do one to maintain my scalp clean (didn't work for me though). 2/4 water (bring to boiled, reduce heat to medium and heat for one hour)...or skip this and just buy a bottle of water :)5 drops of lavender oil (not synthetic).Mix together in a spray bottle and voila! keep in a cool place.
if you want to clean your hair 10 drops lemongrass, 3 tablespoons vinegar, and 1/4 cup water works very well