I wear my dress shirts as a "layer" over a solid-colored T-shirt. I only wear long-sleeve dress shirts by the way. I wear it completely unbuttoned since I like to wear long chains. It's a good way to incorporate different colors into your wardrobe, & I really like the layered look.
Ex. I'll wear a green dress shirt over a red tee [Xmas colors], a pink dress shirt over a purple tee ["real man" colors lol], or a purple dress shirt over a yellow tee [Lakers colors :) ]
Think of the dress shirt as "dressier" than a sweatshirt, but more casual than a formal jacket.
If you wanna know what the described looks is...i have a pic of myself in my profile dressed in the above style.
I will say this...the above style will make you stand out in the crowd of people wear'n tees, polos & sweatshirts. :)
I do this but try not to steal my style. Roll up your sleeves till the elbow and wear it with shorts and rest aviators in the middle where the buttons are as an accessory. I include the shades once in a blue tho