Threading a needle isn't horribly difficult, but it can be a pain if you don't do it regularly. The Art of Manliness has a time-saving tip that makes it much easier: Move the needle to the thread, not the thread to the eye of the needle.
Full disclosure: This is how I've threaded needles for years, and I was surprised when I asked people how they did it, and they explained the various methods of twirling, licking, or narrowing the thread as they try to press it through the eye of the needle. This tip is much simpler. Just pinch the needle down in between your thumb and forefinger so you barely have enough thread to see between your fingers. If you hold it taut enough, it'll be pretty rigid, too.
Then, just move the eye of the needle onto the thread. You'll have more control over the needle and the placement of the eye as opposed to the flexible end of the thread. Try it once or twice, and you'll take to it quickly — once you've done this a few times, you won't do it the other way around ever again. Hit the link below the image to read more.
The Easiest Way to Thread a Needle [The Art of Manliness]