To start, in the spring--usually at least 1 month before the first show, we clip the horses--head to foot--with a #10. that way we can find any --we call them eebbee jeebbees--stuff that is going on under the winter fuzz. We have had some lice, rain rot, and just scaley, scabby stuff that we at least had a month to get cleared up. then about 1 week to 10 days before the first show we will bathe and clip again with a #10. The day before the show (for local shows that are 2 days long) we will clip bridle paths, ears, muzzle, around the top of the hoof with a #30 or #40. making sure to get the muzzle neat since we don't shave the muzzle. We then also clean the hooves. Sanding really rough spots and getting them neat. If we are going to put hoof black on them for show, we will put one coat on at that time also.
Oh, and this fall, we will braid and wrap the tails with vet wrap and open and rewrap every 3 or 4 weeks. We will try to keep the wrapped all show season as well. We never put the up until they are totally dry after a bath. I don't like the way they smell if they don't completely dry first.
The morning of the show--at the show--we will look them over for dirt spots and clipping we may have missed. We will apply another coat of hoof polish. We touch up the show halters. Put them on under their stall halters so they are ready if we happen to miss something and get late. Close to show time, we will put liberal ammounts of fly spray on them. Nothing worse then having flys bite in the ring. We then put some hair gel on the mane to keep it in place. How much really depends on the horse. A little gel will keep that fly-away look on the tail in check as well--just don't make it goopy--just a touch will do.
then I will put baby oil gel above the eyes and on the muzzle. I do use a bit of black chalk on some of the horses with the baby oil, but it is better to put no black on a horse than too much--that is my view. Hubby will make sure he has a bit of grass or hay, a treat and possibly some noisy paper to get the horse's attention in the ring.
Then, last, but not least, have someone look at you or look in a mirror and make sure you don't have a dirt smudge on your face or that your hair is falling where it shouldn't. That is something I see many people forget.
Hope this helps