She's eight. My SD went to 1st grade all spun up because her mom taught her about matching and was so upset about getting it right. She got home and cheerfully announced, "Nobody else knows how to match, either!"
Now, I'm not saying don't care at all but think about what you really need to care about. If your kid has the right insides, does it really matter about socks and capris? If she wears a dress to a wedding like you ask her to, do stripes and dots really matter on a school day or weekend? Does your child really need to be like her best friend?
I would make her be clean and appropriate for the season (no shorts in winter) and then not worry about the rest. My SD still wears two different socks with skirts and chucks and frankly...she's confident, smart, kind and caring. THAT matters more than some of the wackadoodle outfits she puts together. When we need her to, she can also dress to impress or dress for a wedding and not embarass us.
If your DD needs her pants twisted around or a spot check for toothpaste, just do it and chalk it up to being a kid. I used to wonder why little girls have wild hair...until I started spending time with them. ;)
Re the hair, make it a bedtime ritual for it to be brushed and braided so if she runs off without a brushing in the AM, there are a lot fewer tangles. You can also ask her if she'd rather the braiding or shorter hair. My SD was like that til she was about 11.
It'll be alright. Just let her be who she wants to be. One day she'll start taking 45 minute showers, spending 3 hours in the bathroom and missing the bus because she was perfecting her make up. It may not be til she's 14, but most girls generally go through THAT phase, too.
If she wears too short shirts, then go through the outfits with her to take out the stuff she's outgrown so she can more easily make better choices.