Hi OP. It would be helpful to know which ridden class your daughter is entering as some have different requirements to others.
As you say, pony, tack and child should be clean and tidy. How you turn out really depends on the pony's type and the class. So if he's a M&M or a hairy cob then you would not be expected to plait or trim for example.
Again, your daughters outfit will depend on what you are doing (so tweed for M&M, working hunter type, coloured etc and blue of black jacket for riding pony, hack) Neat hair, velvet hat or hat silk to match the jacket, gloves, discreet numnah and minimal bling or fuss. At local level it's not really a huge problem if you don't look completely correct so don't worry too much, the judge will be more concerned with the pony's way of going, and your daughter's riding.
As the previous poster said, most classes will have the entrants walk, trot and canter as a group (if it's a junior class you may not be required to canter and if your daughter doesn't feel confident to do this then just let the stewards know - they will usually allow you to wait in the middle of the ring) The judge will then call everyone in and you then do your individual show. This doesn't need to be fancy, just walk away from the judge and then trot back. Trot a figure of eight and then canter on each rein. Come back to walk and halt and salute before the judge.
The most important thing is that your daughter wears a big smile and has lots of fun!! Please let us know if you need anymore info x