Keep all school uniform in one drawer so your DD knows where to find it, and so you can keep on top of washing etc.
Buy as much school uniform as you can afford - so you don't have to panic-wash everything on Monday night after one single day at school ...
Don't compare your child to others. Don't compare your child to others. DON'T COMPARE YOUR CHILD TO OTHERS. (You will do this, but at least you can have a wry smile when you remember the advice you were given in this post )
Agree with other posters not to do any after-school activities for at least the first term but possibly the whole of the first year at school.
Nametags are well worth the money. And sewing them on is well worth the effort - even those magic laundry marker pens fade after a while.
Never, every criticise anything about the school to any other parent for at least the first term. (If you must do this, do it in private, not on school grounds, and not to a big group of parents).
It doesn't matter if you cry on the first day as you walk away from school, but do not let your DD see you doing this.
It doesn't matter if your DD cries as long as the teacher says she is OK shortly after you've left. This is hard, and may not happen, but if it does - it's normal.
Expect your DD's TV viewing / sulks / sleep problems to increase initially and try not to worry about this - again, 'tis normal.
And the final, most important top tip of all: NEVER, EVER, EVER BE LATE FOR SCHOOL. It is sooooooooo unfair on your child.
Good luck. She will be fine, and so will you.