Granted, it took me years to understand why the buttons I was sewing were so sloppy...the threads weren't uniform and no matter how neat I tried to be, my re-sewn buttons couldn't compare to the factory-sewn buttons on the rest of my garment. Until I took a closer look and realized that I (and probably many others) were doing it all wrong!
In factories, buttons are attached with multiple threads in just one motion--like using embroidery thread (which is comprised of 6 threads). This way, the threaded needle doesn't have to keep going up, and down, and up, and down, etc. You just sew through the shank/holes (depending on type of button) once! Of course, this can be done with embroidery thread, but if that's not available you can use this tutorial to simulate that look.
-Thread, Needle, Scissors/Thread Snips
-Button and Garment to which it will be sewn
-Tailor's Chalk (optional)
If the button has fallen off a garment, such as my coat above, then keep the original thread in it's place for as long as possible. If you feel the button start to loose with wear, pop it off but keep the thread on the garment. The thread will serve as our guide for where to place the button. Alternatively, you can use Tailor's Chalk.
Cut 6 lengths of thread, about a foot each. You can cut up to 8 lengths of thread if you prefer, but bear in mind the weight of the buttons/garment you're working with. Anything longer than a foot becomes difficult to handle.
Roll all of the threads together. Double-knot one end of the threads, and trim and discard the excess.
Level off the other end of the threads and thread the needle.
Remove the original thread from the garment and bring the needle up through one of the small holes left by the original thread. Slide the button onto the needle.
Pull the thread all the way through the material. Bring the needle back down, through the next hole of the button, and through the faint mark left by the original thread. Pull the thread, but not so tight that the button won't be able to slip through the buttonhole.
If you have a 4-holed button, repeat the previous steps. Make sure that the thread isn't holding the button too tightly to the garment. Bring the needle up through the first hole left by the original thread, and loop the thread around, securing your button.
Bring the needle down through the second hole...
...And tie a double knot. Clip and discard the excess thread!
I hope this tutorial helps! I know it's not a sewing breakthrough, but it really took me years to figure out what I was doing wrong. This method is fast and easy, and you couldn't tell my re-sewn buttons from the factory-sewn ones on my coat!