Like all essential oils, cypress oil is concentrated and must be diluted before it comes into contact with the skin. The simplest way is to mix it into an unscented cosmetic base oil such as sweet almond, jojoba, grapeseed, or apricot kernel oil. A reasonable starting point is one drop of cypress oil per teaspoon (5 ml) of base oil; for a larger massage blend, keep the same ratio and add the drops gradually until the scent feels balanced.
For a bath, mix a few drops of cypress oil into a tablespoon of carrier oil or an unscented bath oil first, then add the mix to the bathwater. Because essential oils do not dissolve well in water, this step prevents them from floating on the surface and coming into contact with skin in an undiluted form. The same diluted mixture can also be worked into unscented body lotion, massage cream, or a post-shower body oil.
Cypress has a slightly warming, refreshing woody note, so it pairs naturally with evening baths and massage routines after a long day. If you decide to blend it with other essential oils, keep the total essential-oil concentration low and do not add several strong oils at the same time. Your starting ratio is a safe baseline: you can add more after testing the blend on a small area of skin, but you cannot remove drops once they are already mixed into the oil.