Can you wear navy blue pants with a light blue shirt?

Indeed you can! Accessorize it with a multi-colored belt incorporating the colors. Try to find one with black, and the two shades of blue and red. If you really want to make it pop, wear a hat as well that incorporates these colors. A bright red handbag will really set it off, along with either black, or red strappy, leather heels!
If you are male, I would wear a black leather belt with a silver tone buckel, and a pair of black leather shoes. I would also try to find a suit jacket in Navy blue. To top it all off, wear a bold stainless steel watch! After modeling for 15 years, and now doing photography...Fashion is so much fun! Remember...There are no rules in fashion anymore.....It went out with the 90's. Just have fun!