So many guys make this mistake. Most dress shirts are simply too long and usually a full cut in terms of silhouette so they should be worn tucked in. A trim fit cut is a start, but at least shorter tails if you want to wear it untucked.
How a scarf adds style & flair to a man's outfit. This egotist (Kanye West) actually knows how to dress. Red, black & white Louis Vuitton scarf worn over a white shirt & tucked into a gray/ black & white stripe blazer jacket.