Tying a self tie bow tie can seem a daunting task at first attempt. Have no fear though, it is a lot easier than you think. Essentially you take the same process as tying a shoe and apply it to the bow around your neck. As with anything practice makes perfect. We recommend trying to tie it around your leg while sitting (just above the knee) for practice until you get it just right.
At this point may we again endorse the self tie bow. If you're a big boy, you should be only wearing self tie bows. You no longer wear pre-tied neckties do you? What makes bows so great is how they're tied, makes them unique each time you wear it. For the perfect bow, the know should be a little a-symmetrical. A perfect knot should look unique, just as you are unique. A pre-tied bow will make you look starchy and bland, kind of like a wrapped present with a perfect ribbon bow. Don't be afraid to show your character!
Here are a few videos from GQ Rules and Art of Manliness to get you started!
If the videos didn't help, hopefully this step by step image from Art of Manliness will help. (original article here)