Is there a salon on at the port or on the boat? I think a job is always best with professionals.
If not, and you have your WC do it, I would 100% have a photo of what you want. If you leave it up to a description, then she can interpret it differently than how you meant it, but a picture shows exactly what you want.
You can also have your make up done professionally at a make up counter and have them take the photos of you, this way you can purchase the colors that look best on you and provide them to the WC with a pic of you wearing it. Most times this is free if you purchse x dollars of stuff from the counter.