A basic long black skirt can work with lots of different things. A bell-sleeved high-neck blouse under a corset, a fitted jacket with tails, you could add a bustle to the back of the skirt, etc. Use your own tastes in gothic style to help guide your choices as far as adding in other colors (white, grey, red, purple, and maybe green are solid choices). When one thinks of the goth look, generally a lot of heavy jewelry, jet beads, crosses, rings with bats, skulls, or dragons. Pale skin, dark makeup. Big shoes. Your hair could be styled in a number of different ways, and adding a mini hat is a nice touch. If you want to look more aristocratic than lolita, I wouldn't wear a tiara.
Hope that helps a little.
"And we are all told from the moment we open our eyes, that everyone is entitled to his or her opinion. Well, thatís horsepuckey, of course. We are not entitled to our opinions; we are entitled to our informed opinions. Without research, without background, without understanding, itís nothing. Itís just bibble-babble. Itís like a fart in a wind tunnel, folks." --Harlan Ellison