Warning this is gonna be long so read at your own risk. I know it's last minute seeing how pirate weekend is literally a day or two away, but here is what I do.
Ok so in this upside down poorly lit pic, (sorry 'bout that), I have on the left two skirts, the one that looks black is actually a blue and green plaid cotton blend that was $1 a yard at Walmart and a solid grey cotton blend that was also $1 a yard. Both are extremely light weight and layer well. In the center are my standard muslin poufy shirt and reversable bodice. On the left is a pair of teal pantaloons that are some sort of cotton crepe material.
These are some of my accessories, and a furry friend. Again sorry about the poor quality of the pic, just can't get the lighting right. Going clockwise from the white cresent shaped thing which is called a bum roll. I have a scarf from Target, a hunter green leather hat, a pair of red and black striped hose, a red and white striped long rectangular piece of fabric with chain mail on top of that and a purple belly dancer scarf. In the center is my black uber long leather belt, and ribbons I use to lace my bodice. I change out the color of my lacings to go with my outfits.
Here is how I play pirate... I put on the striped hose with the teal pantaloons and wear my mid calf black granny boots. I combine the muslin shirt, grey bodice and grey skirt. Over the bodice I tie the red and white striped fabric, knot it, and then put the black belt over that. I pull the grey skirt up through the belt. I don't have a pirate hat yet, (I have borrowed one from a friend a time or two), but in the past I have used the same red and white striped fabric to tie a scarf around my head. It's very colorful, but you could go with darker colors. You could do without the hose seeing how you get hot, and sub out socks, but do go with some sort of boot.
I go with the plaid skirt and hunter green leather cap for celtic weekend. I reverse the bodice to the flowered side, wear a feather hair wreath, and a brown skirt I made out of a square of velvet burnout fabric that is midi length when I want a more fairy/hippy look. On those days I go bare legged with flip flops. I also will use the grey side of the bodice with the teal pantaloons, tie the purple belly dancer scarf around my waist and will get a belly dancer/gypsy vibe. On days I'm feeling more like a lady, bodice, skirts, (no hitching), the bum roll, a scarf to cover my hair, (girl with a pearl earring style), and a little basket over my arm because I am going to market after all.
You can literally do thousands of things with just a few skirts, one top, a reversable bodice or two, and accessories. I go with flamboyant color combos, but you can tone down your pirate by changing to darker more traditional colors like going with maroon pantaloons, black and grey scarves, etc. I can tell you that you will do best with something that is easy to wash, throw in the duffel bag and go if you are anything like me. I am happiest at being a wench, looking for my next cup of mead and meeting new people.