As suggested in your other current thread, the #1 priority should be a smooth calm organized ride. (At the schooling show level, this is the major thing to aim for in ANY discipline, and where all too many riders fall short
There is not much you can do between now and the show to constructively change the way you ride, and I don't think it'd be smart to try, outside of the basic "relax your ankles, keep your hands quiet, and look up through the horse's ears not downwards". These are not the most important things of course but they are the only ones that IMO you should even contemplate worrying about at this point.
Remember: the purpose of a show is to SHOW what you and the horse can do, i.e what you DO do most of the time. A show is NOT the time or place to go trying to do things differently! If you go changing what you do, Bad Things tend to happen. Also you won't learn much.
As far as ringcraft, it is no different in hunters than in anything else. Be ready in time (without boring or tiring the hrose with a huge long warmup or sitting around forever and ever), and enter the ring promptly. Try to find a relatively low-traffic part of the rail to occupy, both to be visible to the judge AND to minimize the chance of bad interactions with other horses or getting cut off or things like that. If things go wrong, try to deal with them smoothly.
And, mainly, have FUN (do you sense a theme here) and see how things go and LEARN from everything that happens at the show.
For equitation, appearance matters a little more than in a pleasure class. A lot of hunter people like those checkerboard patterns to brush on a horse's hindquarters, but it is not required.
There are so many things to do before a horse show between horse, tack, your own equipment, etc... Can you be a bit more specific?
I rode on the Arab circuit when I was your age, so we used to do those lovely french-braided manes and fishnet-style too. For open hunter, you're supposed to do the braids, smaller and more closely spaced than dressage braids.
Resist the urge to put Cowboy magic or detangler on the mane before you braid! It makes the hair slippery and it doesn't stay in as well. Just go with the cheapest hair gel you can get!
IF you go to your local tack store or feed store or tractor supply type store you should be able to find horse shampoos, specific for color coats, white, and the like. You can also use bagged chalk to help white the whites even more. Also using a hoof blackner to have all the hooves appear to have the same color is god, or a clear glossy type.
The "fishnet" type is called a continental braid and is used on long maned horses that do not require the shorter hunt or WP type 3 inch length of banding or braid.
If you are showing a horse breed that would other wise have a long mane such as a welsh, arabian, friesian, or gaited breed you can do the french braid or the continental type "braid".
It isn't a true braid but more of a splitting of the sections and rubber bands that create a "fishnet" type of look.
Also very important to remember is DO NOT show sheen or detangler where you you put your saddle.. IT WILL SLIP>.. at the most inopportune time!!
It did for me at a schooling show.
Equitation is also Not so much HOW the horse goes, partially that, but in equitation, its also how YOU look riding the horse.
My sister in law has an older Appendix QH that did barrels.. her head and neck stick way out, and is NOT on the bit... but she wins in english equitation, because what SHE is doing it right...
Hope that helps.. Also google hunter eq and english eq and see what the differences are.
I like combined training.. its dressage then jumping.. dressage, you and the horse are scored doing a pattern.. the jumping.. clean and quick.. you can look like poop, but if you and the horse
get over the jumps fast enough and don't knock any down.. you are good to go!!!
There is a shampoo called Quicksilver<not sure I spelled it right> that will whiten your horse's white spots. I used it on my mare when I showed in AQHA. It will take out grass, dirt, you name it stains.
Remember to keep your shoulders back and your heels down. Look thru the ears. Make sure when you post that your on the right lead. Thumbs up. And most importantly............have fun!!