Here are just some suggestions of what people have said they like how they look on me. Note I am a little bigger than you and I happen to wear shorts year round. Its just my thing, but I can show you some nice shirts that I got.
I have this in a few different colors. It will probably look best a size large, and the slacks obviously depend on the color.
I have this shirt, and in purple. Off all the shirts I own, I get the most complements about the purple shirt.
In general, I find it best to wear darker slacks, as it deemphasizes the gut. I usually mix between dark and light shirts, depending on what shorts I am wearing.