rompers

I would stick to "cute" styles (as people have said, wedges and flats are good) that you would normally pair with a sundress. I'd stay away from sexy pumps/platform sandals because IMO that looks like you're trying a little too hard. I also love the idea of a cardigan over a romper.
 
I think it depends on the romper! I have a bunch of them and some are more casual than others. I have a nautical cotton romper (blue and white striped) that I wear with red espadrille wedges, a pink floral silk romper that I wear out at night with a skinny black leather moto jacket and black studded ankle boots, a tweed gray romper that I wear when the seasons are turning with a long black cardigan and ballet flats...etc.
 
Yeah don't wear heels with a romper. It's too much. Just stick with flats and more low key footwear. I think wedges are okay but since rompers are usually really short your legs will already look long and you don't want them to go crazzzy long. Like disproportionate to the rest of your body, haha.