I'll try, but hopefully someone else will pop in with their experience as well.

Usually people refer to adding a few drops of oil to the distilled water.  Depending on the condition of your hair and the desired effect, you could add more oil.  Be sure to shake the mister well before using so the oil and water will be mixed. 

Some oils can become rancid when left sitting out.  You might want to initially mix a few ounces of water with a couple of drops of oil to test the mixture.  Then determine how much you will use over the course of a week, then you could mix a larger amount.

Let us know what works for you.