Perhaps one of the most difficult things about the saddling up process (for beginners to horseback riding) is putting on the bridle. However, it does not need to be difficult at all, if you will simply take the proper steps to help your horse understand what you are doing.
The first thing you need to do is stand in the correct place, which is just to the left of the horse's shoulder. For most beginners to horseback riding, the tendency is to stand directly in front of the horse, or almost directly in front of the horse. The problem with this is that it makes it very awkward to handle the bridle as you put it on, and it also makes the horse more nervous because you are coming at him in something of an "attack" position from directly in front of his face instead of from a "partner" position, just to the left side of his shoulder.
The second thing is to place the reins over the horse's neck- First the reins, then the bit. This will keep the reins from getting ruined on the ground, will give you a little bit more control of your horse as you can use the reins around the horse's throatlatch to control him and keep him from running off, and will put the entire headstall in a better position to be placed on the horse without resistance.
The third thing is to place the headstall around the horse's muzzle. This will give you added control over your horse, so that you can keep him from learning the bad habit of looking away from you when you attempt to bridle him, and will also keep him from trying to run off. (Many of these kind of habits are easier to prevent in the first place than they are to fix after they have been created.)
The fourth thing is to place your hand properly on the bit itself, so that you can properly guide it into the horse's mouth. You will place your left thumb in the center of the bit's mouthpiece, and your left middle and ring finger into the horse's mouth at the place where the bit will sit. (God has perfectly created the horse so that there are no teeth in the area where the bit will rest.)
Fifth, with your left hand on the bit in this position, you will help him to open his mouth with your left middle and ring finger, as you guide the bit with your thumb at the center of the mouthpiece. Your right hand should be at the top of the headstall between the horse's ears and it is your right hand that will actually pull up on the headstall and put it on while your left hand is simply making sure the bit does not hit your horse's teeth.
Finally, once the bit is in place, you will place the headstall behind the horse's ears and if there is a throatlatch you will buckle it, making sure that there is at least an inch or two of room between the throatlatch and the horse's actual throat because you do not want to restrict the horse's breathing in any way at all, and it simply is not necessary for your throatlatch to be very snug at all. In fact, many of my headstalls do not even have a throatlatch and they have still served quite well both in the arena as well as over many miles of Utah mountain trails here between Zion and Bryce Canyon National Park.
The reason it is so important to bridle your horse this way is that it keeps your horse from getting hit in the mouth with the bit. It is our responsibilty as horseback riders to place a great deal of concern toward the comfort and care of our horses. If we want our horses to truly trust us, then we must be the type of people who care enough about them to take the time to learn how to do things in a way that the horse can understand. This same principle applies, not only to bridling the horse, but also to every aspect of horsemanship.
I understand that there will be an unavoidable learning curve to your horsemanship, but you must make the most diligent effort possible when it comes to treating your horse with respect- and this is exactly why it is so important that you are often riding with people who are better horsemen than you are yourself. You will learn thousands of times more in a single year with an accomplished horseman (if you diligently heed his advice and actions) than you would in a lifetime of struggling on your own.