The hobby standard is to use black oxfords with black tights or knee socks. Not cotton Mary Jane canvas flats, but lace-up shoes. They sort of disappear, or at least become neutral instead saying "LOOK AT MY PURPLE CROCS UNDER MY GOWN!"
Black oxfords can be picked up at Goodwill for a couple of dollars. If you look closely ...
... you can see the padded ankle and the huge clunky heel and the laces, but it general, it doesn't detract from the overall outfit.
When I made the white cross-barred muslin gown for Sweet Daughter, I knew I'd have to step things up a bit. She was going to need white stockings and the shoes were going to be noticeable. I found these shoes,
and thought "What the heck? The price isn't awful, and they have a round toe with no seam, and sort of a buckle ..." The tongues turned out to be absolutely ridiculous, and so I trimmed them back. But not enough ...
And they scuffed terribly after only being worn two days.
They were absolutely "\costume" quality.
So I decided to spray paint them red with Fusion paint designed for plastics. I cut the tongues down some more, masked the heels and soles, and sprayed them red. I figured when they get scuffed up again, I''lljust give them another squirt of red paint.
I ordered some inexpensive oval brass buckles (well inexpensive compared to real shoe buckles) and substituted them for the cheap rectangular pot-metal ones. The shoes are till scuffed, but they look a LOT better.
An easier way to make more passable shoes is to take a pair of thrift store oxfords and cut them down. See the lower profile? Cut down past the first row of grommets. You can touch up the cut edge with a black Sharpie.
Then cut away under the second row of grommets. Cut away so that you have finger-shaped tabs and tie with a silk ribbon.
Same pair of shoes ... after being cut down and before. Quite the difference, eh?
The next project will be thrift store shoes cut down and painted red!