Teaming a beige turtleneck and dress pants will be a good demonstration of your sartorial chops. Now all you need is a pair of black leather chelsea boots to round off your outfit. You can take cues from combinations like this if you're approaching your late 20s and you want to take a more serious direction in your style.
This pairing of a beige turtleneck and dress pants couldn't possibly come across as anything other than seriously dapper and refined. Complete your ensemble with a pair of black velvet loafers and ta-da: this ensemble is complete. As you're going through your late 20s, you probably want to start dressing in a classier manner. In this case, outfits like this are a safe option.