If you have a blue and white striped shirt in your wardrobe, it is fine; otherwise, buy a cheap shirt from any store. A long-sleeved shirt should be preferred.
Buy a navy blue skirt with a reasonable length. It should end 3 to 4 inches above your knees, not too short or too long.
You will further need a red scarf or ascot to wrap around your neck. A shorter scarf will look nice, rather than a long one.
You can get a cheap sailor hat at any party store and it won’t cost you much.
Blue flat shoes will look good with your sailor girl outfit but black shoes will also serve the purpose.
Tuck your shirt into your skirt and wrap up the scarf around your neck. You can knot the ascot lie a tie around your neck as well.
Appropriate jewellery will be a nice add-on to your appearance. Try to find earrings shaped like anchors and a similar sort of a pendant for your neck.
No heavy makeup is required and you should try to give a natural look. However, a red lipstick will really look nice.
Chose a navy blue nail polish to paint your nails for a complete package.