Not sure how much I can help. I did hitchhike around Caribbean
in my twenties. Trick is to get a good boat
Be upfront about your experience level, it is not as big of a liability as you may think.
Look for well maintained vessel
Look for happy crew already aboard or a reference to someone you can speak with who has crewed for that vessel.
Look for easygoing schedule, tight schedules can be hard on crew.
Look for a captain
who is willing to keep you on if you are unable to find crew job( customs
may not let him leave without you, unless you have a plane ticket or position aboard another boat).
For me, since I was a young female traveling alone, I always had an agreement with the captain
that if I could not find a position aboard another vessel, and they couldn't keep me on, they would provide air fare home, that only happened once. Once you make landfall, it usually only takes a day to a week to find a position on another good boat. Many times I was meeting up with another vessel in my next port, so would hop right off of one boat onto another
Listen to your inner voice, if you get a bad vibe from a captain, boat, or crew, move on, and that includes your partner too, she should have automatic veto power.
Hope that helps. Each of you should have a good harness and tether, good sailor knife, flashlight and know basic knots.