You need to be careful with essential oils because they are volatile--especially citrus oils...
For bath salts, add NO MORE than 6-7 drops per bath... and do not use oils such as cinnamon or clove which will irritate nether regions. Most customers will fall prey to the "if one scoop is good, two must be better!" perception and that needs to be accounted for... I would *never* use essential oils by "just adding some until it smells good"-- essential oils have huge benefits but can also be dangerous because they are so concentrated-- a generalization is: for leave on products, keep to .5-1%--for rinse off, keep to less than 3%.