The list is endless.
You should have a couple of skirts and tops, shoes to go with them, bras, panties, at least one slip, and stockings. A wig is a necessity, unless you can style your own hair to make it look feminine. You need some kind of breast form--this can be as cheap as a pair of stockings stuffed with birdseed to expensive breast forms. You need makeup--I consider eyeshadow, eyeliner, mascara, powder, blush, lipstick, and nail polish to be essential. Along with makeup you should have skin care products--good cleanser and moisturizer. Jewelry is also important to accesorize your look--I am partial to earrings, necklaces, and bracelets; I also have an inexpensive ladies' watch.
There is no end to the way you can mix and match these items. Suppose you see a cute skirt that you like. Well, then you need to ask whether you have a top that matches it. If not you need to look for a top. And what shoes would go well with that? Should I wear pearls with that or would a gold chain be better? Would this look better if I wore the dark eyeshadow and a subtle pink lipstick or should I go with the darker lips and a more natural eyeshadow? The fun is just beginning and there is no end to it.