I dunno about a lady pirate's items or outfits or whatever, ummm.. What I don't recommend is writing her as a male and then just making her a female at the last second. While, yeah, I guess you can do that, idk.. I can't put my finger on it, but I know something would be off. I personally like to seeing a female leader and having her gender affect her experiences because if it's the same journey that a man could've taken.. well, I'd have to wonder why the character had to be a woman to begin with.
There's also the usual "don't write a Mary Sue," I guess. Don't do that either lol make her flawed! Flaws and tradeoffs make characters interesting! Easy example, she could be great at looting, but she doesn't know when to stop!
This isn't so much advice on writing her, but you can always show her crewmates' thoughts about her. You can always use it as a reference of how to write her. Are there a few who see her as brilliant leader? Are there those that see her as inferior based on her gender? Coming up with and answering similar questions can help flesh her out more.
Good luck~