It is very important that you cross the left and right strands under the middle one and not over, otherwise you'll get a French braid instead.
I've been here forever and invented a few myself.
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Tuck the tail-end of the braid underneath the braid, then secure everything with bobby pins.
Keep going until the bun reaches the hair tie.
Recently I learned how to do a messy orchid bun orchid bun but with my hair it comes out messy, I may not have enough length to be able to do an orchid bun that is not messy but I'm not comfortable with it to the point of not needing the instructions.