If you pull the tail well at the beggining of the show season you only occassionaly need to give it a 5 min tidy up throughout the rest of the season.
Right to pull a tail you are essentialy doing the same as you are on the mane, you select a chunk of hair, back comb and pull! On the mane you want to take hair from underneath and pull so that the mane is level
However for the tail you need to litteraly do it a few hairs at a time and if your horse is a sensitive soul then you need to do it over the course of a few days.
Before you set to work look at the shape of your horses quarters and watch how he carries his tail. This will enable you to judge correctly how far down the dock you are going to need to pull in order to achieve the desired effect.
Wear a pair of thin rubber gloves when tail pulling as it will help you get a better grip on the hair and give some protection against blisters. Surgical gloves are ideal. A pair of pliers also comes in handy for those short hairs you just can't grip
Start at the sides of the dock, lift the top hairs, taking hair from underneath and equally on both sides pull downwards taking small amounts each time so you don't leave bald patches. Stop at regular intervals, stand back and see which areas need more attention, remember you can always take more off you can't stick it back on again. You will probably also have to remove hair from the top of the tail to reduce the thickness and allow the hair to lie flat.
Applying a tail bandage for short periods will help flatten the hair and train the shape of the tail.
Remember the most important thing is that you pull very small amounts at a time, stop if the dock bleeds and continue the next day. Never attempt to pull a tail in one day