Maintain proper hygiene: shower regularly, brush/gargle/floss, take care of your skin..
Also look presentable while in public. I absolutely cannot stand it when guys wear sweat pants and gym shorts outside of a gym. It doesn't take any longer to put on a nice pair of shorts or slacks than it does to put on sweat pants. Find your own style and work with that depending on the day and how you're feeling. Ex. if you're heading to the store and you don't feel like dressing up too much, then simplify what you usually wear. That could be the basics www.kinowear.com/.../
-Clean cut -Great hygiene -Coordinate his outfit well -Have his clothes look clean and nicely ironed. -Add accessory to liven up his outfit (if he may)---a hat, a nice watch, or sunglasses always does the trick.
Shower daily, keep your face neatly shaved, wear clothes that fit you nicely, (not too short/tight, not too long/baggy) smile, keep profanity at a minim, have confidence. I guess the 3 main things are well groomed, confidence, and kindness. If you have that, you should look your best :)