Let's be honest. Summer dresses are basically sheerer and rank from slightly sheer to transparent. It is often considered as a picnic dressing than a formal way of dressing. Many women still consider that wearing sheer is not modest and slightly on the slutty side.
But if you consider wearing a sheer blouse to formal or casual occasions, you have many ways to do it.
The first and obvious thing to do when wearing a sheer top is to simply wear a tank or camisole underneath it. You can choose a tank of matching color that of your sheer top or simply mix and match with opposite colors to enhance the top. It all depends on your mood and occasion.
Remember a sheer top can still be modest if worn correctly.