Bleh, realistic wishes are lame. D:
But I guess, if it has to be realistic, I'd wish for something like knowing a whole lot about stuff, especially astrophysics. That'd make life soooo much easier since I plan to be an astrophysicist. Not to mention I'd have the mind to back up my mouth. I mean, I am rather smart, but I know I often pretend to be smarter than I really am because it makes me feel important. :D
Of course, another sensible thing to wish for would be better social skills. They wouldn't even have to be outstanding, as long as I was a bit better at talking to people.