Strat nearest the ears, take 3 small sections of hair, cross the top over as if you were starting a plait, when you cross the 3rd bit down over, pull a small section of the mane just beyond it in as well, carry on as if plaiting but each time move a small section in on the 3rd cross-over. You can keep it as tight or loose to the neck as you like- I tend to find they stay in better if you have them tight to the neck and gradually let it come down towards the end.
Years ago I used to plait my cob right down the crest by parting the mane onto both sides of the neck then start by taking a bit from each side into the middle for one strand then pick up the strands from the outside and plait right down in the same way. Plait the long end down at the wither and either leave it long or turn it in half. It takes a bit of practice to keep it high on the crest but is very smart when done right, I used to do it sitting on the horse!
start at the top of the head, then just like a normal fench plait. everytime you bring a piece of mane from left to right add a bit more at a time in from the botton
not the best pic as was done in a rush just to keep mane out the way and keep her neck fro sweating up as much