There are many possible ways to thread a needle. Many tailors and seamstresses would argue that, by far, the easiest way to thread sewing needles is to use a needle threader. That task is, after all, what the tool was designed and manufactured to perform.
A needle threader is a small tool made up of a single piece of thin, bent wire through which one end of a string of thread is meant to be inserted. The wire is much easier to thread through the eyes of sewing needles than the thread itself. After pushing the wire through the needle, the thread is then looped through the piece of wire once. The wire is retracted back through the eye of the needle, pulling the thread with it. After removing the needle threader from the thread, the thread remains passed through the eye of the needle.
Other methods to ease the difficulty of threading sewing needles include treating the thread and creating easy visualizing conditions. It is recommended by needlepoint workers to cut thread at an angle, creating a sharp point as this is easier to string through a sewing needle than a blunt end. If the thread bends too easily when pressure is applied or if there are too many free fibers coming off the end of the thread to easily push the thread through the eye of the needle, one should wet the thread to give it weight and remove the extraneous fibers.
Good lighting is invaluable for threading sewing needles, as is finding an object that contrasts with the color of the thread. One common mistake in attempting to thread sewing needles is not paying attention to creating conditions that allow a user to easily visualize the thread and the eye of the needle. If the thread is a dark color, one should thread a needle over a white background, like a piece of paper. Many people find it useful to aim a nearby lamp at the workspace to easily see the thread and the eye of the sewing needle.
When other methods have failed, many tailors will hold a piece of freshly cut thread between a thumb and forefinger and press the eye of a needle onto the thread, not allowing the thread to move. This method works if the tailor has steady hands and can easily place the eye of the needle over the thread. The downside of this method is that it does have a tendency to ruin the end of the thread if the target of the eye on a sewing needle is missed.