There are two factors involved in bridlewear; fit and balance. These two points come together during the process, but to clarify;
FIT. A bridle must have good clearance behind the ears. The browband needs to be tight enough to sit gently on the forehead, but not too tight that it pulls the headpiece forward. The throat latch should be a hands width from the jowl of the horse. The cheeks piece need to be done up so the bit gives two gentle crinkles to the corner of the mouth and finally the noseband should sit 2 fingers below the cheek bone and allow a finger to slide inside.
BALANCE. The balance of the bridle gives an overall look of correctness. When considering balance you need to think of the discipline that the horse is doing, the type of work involved and what type of head the horse has. All buckles should be sitting on the middle hole and be done up at eye level. This gives a very clean appearance to the bridle. The width of the strapping should not only suit the horses head and neither be lost or overpower the head, but should be appropriate for the discipline. A fine Turnout bridle would not be appropriate for galloping across country.
Colour also comes into balance. Although matching exactly to the saddle colour is appropriate for turnout, it isn’t always the most flattering for the head. A Dark Havana bridle can look much better on a Chestnut, giving a warmer feel and can still be worn with a black saddle.
When you have the correct fit with a good balance, the appearance should be clean.