Here are the rules in my house:
-- We do not wear PJ's out of the house.
-- We do not wear dress up clothes out of the yard. (the dress up jewlery she can wear when we are out and about, because she wants to wear a necklace like mommy)
My daughter knows which are the PJ, tops, bottoms & underwear/sock drawers. So if asked she gets items out of the apporiate drawer. On days that I know we are visiting friends or family, or going out to eat I will give her a choice of this outfit or that outfit. Of course we have talked about being weather apporiate and she understands that.
Now at age 5 she may say can I wear something pink or purple so I find something that matches. When just running errands I let her dress herself, after a few months she has started to get the idea of matching. I have done this by saying well the skirt has blue, green and pink it in so try to find a top that is blue, green or pink. Now if it is not a perfect match that is fine, it is a learning experiance.