Sorry to bust your bubble hon, but your chances of becoming a geisha is slim and none. You have a better chance of being elected for president than becoming a Geisha in Japan.
Firstly, Japan is NOT a society like America where anyone can become anything they want regardless of race. They are not kind to foreigners (black, white or any other) at all, and not only will they be cruel to someone white who tries to become a legitimate Geisha (and not as some sort of experiment), they are not going to approve of you at all. If anything, you will be totally scorned. A geisha is a cultural icon, and i something that is culturally important to the Japanese. That, and Samurai, are the things that many people think of when they think of Japan. Japan is nationalistic and very xenophobic. It's not even that they're racist, because they dislike EVERYONE, regardless of color.
Additionally, a lot of people ask this because the lifestyle of a Geisha and anything Japan related is a trend in the US. Most Americans would not be able to last 5 minutes under the training that Geisha receive, and under the rigid system and physically draining hours that maiko/Geisha go through. You have to be able to perform well, bring in a good amount of money, have lots of clients and be in DEMAND. It is highly stressful.
Another reason why it will not ever work for you is in regards to makeup and facial features. It's one thing to simply dress in a kimono or a hikizuri. I've dressed in a hikizuri before (from a friend), and I've been told that I look good in it, but as a Geisha, I wouldn't dare ask that of myself. Our skin does not, and will not, look good under pure white makeup, no matter how many layers are added. Also, our facial features are way different from those of the Japanese. Even white touristy geisha don't look at all convincing, and some can look just plain foul. I say this as a person who has gone to Kyoto quite a few times.
All in all, you can speak to geisha and become fond of the Japanese arts and become an art enthusiast, or even an anthropologist, but as far as you becoming a geisha, don't bet on it. Ever. You can also dress as a maiko at an anime convention. I'm actually good with maiko makeup myself (I've been studying geisha culture since I was 16. I'm 21), so if you have any questions, I can tell you about applying it. However, as a fellow black woman, I would totally advise against it, 100%.