If you want to wear khakis, just make sure they fit correctly.
Having a matching belt and shoes is key, in this case brown is ideal. Make sure your color pallet is fluid and appealing to the human eyes.
As for a shirt, navy blue is fine, as long as its tucked and you are somewhat thin.
To make this fit even better, you could wear a light blue or pale pink button up tucked in. With a navy blazer over top, unbuttoned.
This is a pretty safe/common look.