"Uh, genie, isn't something supposed to happen? Did it not work?" you ask doubtfully. You still look exactly the same in the mirror, and nothing around you seems different.
"Of course it worked!" the genie scoffs at you, a bit annoyed at your doubts. "You are now an immortal shapeshifter in total control of her powers, so nothing will change unless you change yourself."
"And I do that...how?" you ask, a bit chastened but still unsure.
"Beats me," the genie replies with a snort. "You wished for control over your powers, not the knowledge of how to control them."
"So then if I wish for--" you start but the genie cuts you off.
"I told you, I only deal in transformation wishes. Knowledge has nothing to do with transformation, so that's out," the genie says dismissively, then stretches and yawns. "Well then, now that that's done, I'm taking a nap. See you, hopefully not for a few thousand years," the genie waves and poofs back into his bottle.
"Wait!" you call out, but it's too late. You could always rub the bottle again, but what use would that be? Like the genie said, you can't wish for knowledge because that doesn't have a transformation aspect. Even if you wished for a bigger brain or something like that, it wouldn't help you figure out how your powers worked. You would just have to deal with trial and error.
Standing in front of the mirror, you contemplate how to change yourself. Do you just have to think it? Turn my hair green, you squint and concentrate, but nothing happens. Are there other variables involved? Will you spend the rest of your now eternal life figuring out how to do it? And even if you are immortal, will your body still age at a normal rate? Does that mean if you can't figure out your powers, you'll be an immortal decrepit old woman?
Maybe you could look for another genie, but what're the chances of finding one, and one that doesn't have weird restrictions like the one you got? You should probably spend more time trying to figure this out first. Maybe later you could go online or to the library and look for information on shapeshifters.
Deciding to try again, you close your eyes this time and focus. Maybe something simpler first. Make the hair on my head grow, you think to yourself, but this time you try to imagine hair getting longer. You are not sure if you are imagining it, but your head feels a little warm and tingly. Did you figure it out?
You squint open one eye, then the other, then your jaw drops. You grew hair all right. Just not the hair you intended. Now you are sporting a nice, full beard. At least, it would be nice, if you weren't a woman.
"Aw, crap," you curse, then wonder if you need to learn how to shave your face.