Fitting the English snaffle or, rather, the English noseband, should be easy for every rider. However, sometimes the noseband gets fastened too tightly, which can cause pain to your horse. If you adjust your snaffle bridle correctly, it should be tightly fastened two finger widths below the cheekbone and loose enough so that you can easily reach underneath with two fingers next to each other.
The throatlatch should be loose enough so that you can place your clenched fist between the horse's head and the throatlatch.  The throat lash should fit snugly and smoothly. If it is too loose it can slip down or lose its effect. If it is too tight then it will be very uncomfortable for the horse and will cause a problem. If you fit your English snaffle correctly, it will support you and your horse in communicating via your aids.