First, make sure your suit is the right size. Any major department store can measure you and fit you for the correct size suit. Your suit shouldn't overlap in the front, but it should be able to be buttoned comfortably. Your jacket should not be pulling in the back or across the front. Your pants should not be bunched up at the end, but should rest comfortably at the top of your shoe and fall to the bottom of your heel. Every man that wears suits regularly should have a gray, navy, and tan suit. Keep it simple and classic with suits!
Stay away from bright solid-colored shirts. (Especially ones with matching ties in boxes, actually stay away from ALL boxed shirts/ties!) You should have shirts that match all your suits and that are remixable with many different ties. Try to keep it to classic colors, white, blue, and light colored patterned shirts. Never dry your dress shirts. That makes the collars deformed and the color fade. Hang up and iron your shirts. Nothing worse than seeing a man in a wrinkled dress shirt.
Graphics, words, cartoons, etc... are a NO-NO! Keep it classic, with stripes, polka dots, or solids.
Square toed dress shoes are not "in" right now. Instead, look for round toed brown dress shoes. Cole Haan are the most comfortable and nicest leather. Here's an example of nice dress shoes.
Look for darker wash jeans. Make sure your jeans fit correctly. Not super relaxed, but not skinny jeans either. Find the perfect happy-medium. Currently, my favorite jeans are Buffalo Jeans. Don't forget you can always ask your wife for her opinion.
No tennis shoes with jeans! There is a difference between casual wear and active wear. Tennis shoes are meant for sports/working out. Find some nice casual brown shoes. Sperry's or Toms are a great casual shoe.