The throatlatch should be neither tight and constricting nor loose and flopping. All straps should be tucked neatly into their keepers and the crownpiece of the caveson hanger should be completely covered by the main crownpiece.
The buckles on a hunter bridle are usually silver and square shaped and will have two keepers--one fixed into position beneath the buckle and the other sliding. The cheekpiece buckles should lie even with or slightly higher than the back corner of the horse's eye. Although you may see a lot of model bridles with the buckle placed below the horse's eye, that is extremely uncommon on real show bridles and would generally indicate the bridle is much too small.
Helpful? Please let me know!