First find a long-sleeved white shirt--the puffier the sleeves, the better. A few ruffles at the neck add a nice piratey touch. (Guys, you might have to raid a girl friend's closet.) Keep your shirt open at the neck.
You can wear the dark pants several ways. If you have knee boots, stuff the pants legs into the boots. If they are too bulky, cut off a few inches below the knee, and then stuff them in. Long black socks can be used instead of boots. Just cut the pants off to the length you want, leave them ravelled, and let them hang over your socks.
Use a scrap of fabric for a waistband. The material should be long enough to fit around your waist with several inches left over. Solid colors or small red or black stripes work well. Scrunch up the cloth, wrap it around your waist and tie it in a knot.
Now for the "accessories". Tie a bandanna around your head--Harley style. Here's where you can have some fun--bandannas come in all kinds of colors and designs. Be creative! Dig through the costume jewelry and find some bling such as hoop earrings and big chains. You can make an eye patch from thin elastic and a scrap of black fabric. Cut a patch shape out of the fabric. Measure enough elastic to fit around your head, and sew the ends onto the black fabric. A sword can be made from cardboard and aluminum foil.