I was shown the "correct" way to bridle a horse is to put the bridle in your right hand, raise the bridle up over your horse's head, hold and insert bit.  Well that just didn't work for me.  Many horses will throw their head up, or swing their head away from you.  Some even lower their head to the ground to avoid that dreadful thing. 

       What I've learned is to hold the bridle in my left hand with my right arm under the horse's chin, and my right hand over his nose.  In this way I can keep his head up from trying to 'root', and the hand on his nose counteracts the tossing and swinging. 

        When working with a young horse, one who has never been bridled before, I first handle the head in the above manner without the use of the bridle.  Frequently, I will gently hold the horse's head to the side of his body, asking, not forcing, him to keep it there, like giving him a hug.  I begin to stroke his head and ask him to relax. This does a few things, first it gets the horse used to being touched and restrained just a little, it also puts the horse's head in a "calm down" position. 

        Next I begin by softly massaging inside the horse's mouth with my fingers, I watch for him to lick, and quickly remove my fingers.  He learns that it is OK for something foreign to enter in.  Once the horse accepts this feeling, I am ready to add the bridle.  I hold the bridle in my left hand and position the bit at the separation of the lips, holding it with the fingers of my right hand.  I ask the horse to lick again using my thumb to cue him, and when he is ready I insert the bit.  Easy does it, so as to not bump his teeth.  The trick to this is teaching the horse to "open wide". 

        Using this method has been very successful for me.  My horses see me coming with the bridle, and they begin to yawn.  They open wide and are very easy to bridle.

A word of caution:  Removing the bridle is where most mistakes are made and why horses dislike bridles.  When you remove the headstall from the ears, be sure to hold it up, and not drop the bit down onto the teeth.  Keep the horse's nose downward, and when the horse opens wide and begins to lick, gently lower the bridle and let the horse "spit" the bit out. 
Psalm 37:4