I think that the traditionally correct side to braid the mane on is the right side (right from the back of the horse, not looking at them head-on). I've always done around 30-40 braids- it's less for dressage (that's what I've heard and seen) and generally more for hunters.
Those really aren't bad at all charliBum... I personally like mine to sit out and up a bit more..... have to take some pics when I next do some... :) a video is a great idea- especially to help those who have never done their own before
When need some extra cash, I also groom for the riders where I board.
Back when I was taught to braid, I was taught its an even number including the forelock.
I don't sew my braids in but I find that they stay in quite well. I find the braids turn out neater if you start off by banding them first. And always make sure the part is straight in between braids, you don't want it to look mish-mashed and bodgy.
Most of the horses I braid have about 10-16 braids including the forelock. I think the best tip I can tell you is to braid to make the neck look good.
I've never braided for a hunter, but from the researching (googling) I just did, the more the better.