One aspect of style is taking an article of clothing and wearing it a bit differently. Example.
He’s popped his jacket collar. His belt is askew. His pants are rolled.
All of these are good ways to make a dressed-up look come across more casually. It demonstrates attitude and a tongue-in-cheek disregard for rules and norms. Since this guy is a model and is being photographed for a catalog, he can get away with all three. My suggestion is to start off with one and then work your way up from there.
I rolled my khakis all summer last year and it not only looked different but was actually more comfortable. Imagine that – form and function in one happy place.
Also, lavender is a good shirt color.