This is a test of commonsense. Complete the next sentence:

How to bridle a horse
Check that you have the correct bridle size.
If this is the first time you're using this bit on this particular horse you should be sure that you're using a proper sized bridle. If it's the wrong size it will make the horse uncomfortable.
Bridles comes in three sizes: pony, cob or arabian, and full. Measure your horse's head from the center of his poll to the corner of his mouth, and compare this measurement to the crown and cheek piece of the bridle.