Go to local competitions. If you review the threads, you'll see all sorts of debates over "what is appropriate". In my region, what other regions consider to be "okay" would be considered to be garish and over the top. So, you need to go see what other kids at your kids level wear, and go from there. From the perspective of a judge in our region, which my DD is, they like to see little girls dressed as little girls, in modest dresses that look warm and comfortable. They dislike illusion, bare arms, shoulders, etc, and excessive rhinestoning ... yet, in other areas, apparently those sorts of dresses are the norm!
In terms of practice clothing, again, go to the rink. See what the little girls wear. If they wear skirts ... wear a skirt. If they wear pants ... wear pants. Just make sure that it's practical, comfortable, and within your budget. Don't blow your cash chasing the fanciest clothes you can afford, and be sure to check out the used skating clothing sales to save $$$. You do want your kid to fit in, but, not if it is at the expense of lessons.
Spend your money on skates that are right for her level, good coaching, and a good pair of hard guards. Skating is notorious for flash and cash type stuff; Zuca bags are one of my pet peeves, as little girls get them, and yet, their parents wail over the cost of skating lessons and skates (can't figure that one out).
And, very importantly, stick to your values. If you think something is inappropriate or overly expensive, then, don't buy it. You have to start early with your daughter to let her know the difference between "needs" and "wants" and what budget means, which will help you keep costs under control.